Tag Archives: Earth and Planetary Astrophysics

Unsigned magnetic flux proxy from solar optical intensity spectra [EPA]

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http://arxiv.org/abs/2305.03522


The photospheric unsigned magnetic flux has been shown to be highly correlated with radial velocity (RV) variations caused by solar surface activity. This activity indicator is therefore a prime candidate to unlock the potential of RV surveys to discover Earth twins orbiting Sun-like stars. We show for the first time how a precise proxy of the unsigned magnetic flux ($\Delta\alpha B^2$) can be obtained from Sun-as-a-star intensity spectra by harnessing the magnetic information contained in over 4000 absorption lines in the wavelength range from 380 to 690 nm. This novel activity proxy can thus be obtained from the same spectra from which RVs are routinely extracted. We derived $\Delta\alpha B^2$ from 500 randomly selected spectra from the HARPS-N public solar data set, which spans from 2015 to 2018. We compared our estimates with the unsigned magnetic flux values from the Solar Dynamics Observatory (SDO) finding excellent agreement (median absolute deviation: 4.9 per cent). The extracted indicator $\Delta\alpha B^2$ correlates with SDO’s unsigned magnetic flux estimates on the solar rotational timescale (Pearson correlation coefficient 0.67) and on the three-year timescale of our data set (correlation coefficient 0.91). We find correlations of $\Delta\alpha B^2$ with the HARPS-N solar RV variations of 0.49 on the rotational timescale and 0.78 on the three-year timescale. The Pearson correlation of $\Delta\alpha B^2$ with the RVs is found to be greater than the correlation of the classical activity indicators with the RVs. For solar-type stars, $\Delta\alpha B^2$ therefore represents the best simultaneous activity proxy known to date.

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F. Lienhard, A. Mortier, H. Cegla, et. al.
Mon, 8 May 23
59/63

Comments: 17 pages, 10 figures, accepted for publication in MNRAS

Tidally Heated Exomoons around $ε$ Eridani b: Observability and prospects for characterization [EPA]

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http://arxiv.org/abs/2305.03410


Exomoons are expected to orbit gas giant exoplanets just as moons orbit solar system planets. Tidal heating is present in solar system satellites and it can heat up their interior depending on their orbital and interior properties. We aim to identify a Tidally Heated Exomoon’s (THEM) orbital parameter space that would make it observable in infrared wavelengths with MIRI/JWST around $\epsilon$ Eridani b. We study the possible constraints on orbital eccentricity and interior properties that a successful THEM detection in infrared wavelengths can bring. We also investigate what exomoon properties need to be independently known in order to place these constraints. We use a coupled thermal-tidal model to find stable equilibrium points between the tidally produced heat and heat transported within a moon. For the latter, we consider a spherical and radially symmetric satellite with heat being transported via magma advection in a sub-layer of melt (asthenosphere) and convection in the lower mantle. We incorporate uncertainties in the interior and tidal model parameters to assess the fraction of simulated moons that would be observable with MIRI. We find that a $2 R_{Io}$ THEM orbiting $\epsilon$ Eridani b with an eccentricity of 0.02, would need to have a semi-major axis of 4 planetary Roche-radii for 100% of the simulations to produce an observable moon. These values are comparable with the orbital properties of gas giant solar system satellites. We place similar constraints for eccentricities up to 0.1. We conclude that if the semi-major axis and radius of the moon are known (eg. with exomoon transits), tidal dissipation can constrain the orbital eccentricity and interior properties of the satellite, such as the presence of melt and the thickness of the melt containing sub-layer.

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E. Kleisioti, D. Dirkx, M. Rovira-Navarro, et. al.
Mon, 8 May 23
63/63

Comments: N/A

Three-dimensional orbit of AC Her determined: Binary-induced truncation cannot explain the large cavity in this post-AGB transition disk [EPA]

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http://arxiv.org/abs/2305.02408


Some evolved binaries, namely post-asymptotic giant branch binaries, are surrounded by stable and massive circumbinary disks similar to protoplanetary disks found around young stars. Around 10% of these disks are transition disks: they have a large inner cavity in the dust. Previous interferometric measurements and modeling have ruled out the cavity being formed by dust sublimation and suggested that the cavity is due to a massive circumbinary planet that traps the dust in the disk and produces the observed depletion of refractory elements on the surface of the post-AGB star. In this study, we test alternative scenario in which the large cavity could be due to dynamical truncation from the inner binary. We performed near-infrared interferometric observations with the CHARA Array on the archetype of such a transition disk around a post-AGB binary: AC Her. We detect the companion at ten epochs over 4 years and determine the 3-dimensional orbit using these astrometric measurements in combination with the radial velocity time series. This is the first astrometric orbit constructed for a post-AGB binary system. We derive the best-fit orbit with a semi-major axis $2.01 \pm 0.01$ mas ($2.83\pm0.08$ au), inclination $(142.9 \pm 1.1)^\circ$ and longitude of the ascending node $(155.1 \pm 1.8)^\circ$. We find that the theoretical dynamical truncation and dust sublimation radius are at least $\sim3\times$ smaller than the observed inner disk radius ($\sim21.5$ mas or 30 au). This strengthens the hypothesis that the origin of such a cavity is due to the presence of a circumbinary planet.

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N. Anugu, J. Kluska, T. Gardner, et. al.
Fri, 5 May 23
9/67

Comments: Accepted to be published in The Astrophysical Journal

The edge-on protoplanetary disk HH 48 NE I. Modeling the geometry and stellar parameters [EPA]

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http://arxiv.org/abs/2305.02338


Context. Observations of edge-on disks are an important tool for constraining general protoplanetary disk properties that cannot be determined in any other way. However, most radiative transfer models cannot simultaneously reproduce the spectral energy distributions (SEDs) and resolved scattered light and submillimeter observations of these systems, due to the differences in geometry and dust properties at different wavelengths. Aims. We simultaneously constrain the geometry of the edge-on protoplanetary disk HH 48 NE and the characteristics of the host star. HH 48 NE is part of the JWST early release science program Ice Age. This work serves as a stepping stone towards a better understanding of the disk physical structure and icy chemistry in this particular source. This kind of modeling lays the groundwork for studying other edge-on sources to be observed with the JWST. Methods. We fit a parameterized dust model to HH 48 NE by coupling the radiative transfer code RADMC-3D and an MCMC framework. The dust structure was fitted independently to a compiled SED, a scattered light image at 0.8 ${\mu}$m and an ALMA dust continuum observation at 890 ${\mu}$m. Results. We find that 90% of the dust mass in HH 48 NE is settled to the disk midplane, less than in average disks, and that the atmospheric layers of the disk contain exclusively large grains (0.3-10 ${\mu}$m). The exclusion of small grains in the upper atmosphere likely has important consequences for the chemistry due to the deep penetration of high-energy photons. The addition of a relatively large cavity (ca. 50 au in radius) is necessary to explain the strong mid-infrared emission, and to fit the scattered light and continuum observations simultaneously.

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J. Sturm, M. McClure, C. Law, et. al.
Fri, 5 May 23
10/67

Comments: 16 pages, 8 figures, accepted for publication in Astronomy & Astrophysics

Multiplicity Boost Of Transit Signal Classifiers: Validation of 69 New Exoplanets Using The Multiplicity Boost of ExoMiner [EPA]

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http://arxiv.org/abs/2305.02470


Most existing exoplanets are discovered using validation techniques rather than being confirmed by complementary observations. These techniques generate a score that is typically the probability of the transit signal being an exoplanet (y(x)=exoplanet) given some information related to that signal (represented by x). Except for the validation technique in Rowe et al. (2014) that uses multiplicity information to generate these probability scores, the existing validation techniques ignore the multiplicity boost information. In this work, we introduce a framework with the following premise: given an existing transit signal vetter (classifier), improve its performance using multiplicity information. We apply this framework to several existing classifiers, which include vespa (Morton et al. 2016), Robovetter (Coughlin et al. 2017), AstroNet (Shallue & Vanderburg 2018), ExoNet (Ansdel et al. 2018), GPC and RFC (Armstrong et al. 2020), and ExoMiner (Valizadegan et al. 2022), to support our claim that this framework is able to improve the performance of a given classifier. We then use the proposed multiplicity boost framework for ExoMiner V1.2, which addresses some of the shortcomings of the original ExoMiner classifier (Valizadegan et al. 2022), and validate 69 new exoplanets for systems with multiple KOIs from the Kepler catalog.

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H. Valizadegan, M. Martinho, J. Jenkins, et. al.
Fri, 5 May 23
24/67

Comments: N/A

The edge-on protoplanetary disk HH 48 NE II. Modeling ices and silicates [EPA]

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http://arxiv.org/abs/2305.02355


The abundance and distribution of ice in protoplanetary disks (PPD) is critical to understand the linkage between the composition of circumstellar matter and the composition of exoplanets. Edge-on PPDs are a useful tool to constrain such ice composition and its location in the disk, as ice spectral signatures can be observed in absorption against the continuum emission arising from the warmer central disk regions. The aim of this work is to model ice absorption features in PPDs and determine how well the abundance of the main ice species across the disk can be determined within the uncertainty of the physical parameter space. The edge-on PPD around HH 48 NE, a target of the JWST ERS program IceAge, is used as a reference system. We use RADMC-3D to raytrace the mid-infrared continuum. Using a constant parameterized ice abundance, ice opacities are added to the dust opacity in regions wherever the disk is cold enough for the main carbon, oxygen and nitrogen carriers to freeze out. The global abundance of the main ice carriers in HH 48 NE can be determined within a factor of 3, when taking the uncertainty of the physical parameters into account. Ice features in PPDs can be saturated at an optical depth <1, due to local saturation. Spatially observed ice optical depths cannot be directly related to column densities due to radiative transfer effects. Vertical snowlines will not be a clear transition due to the radially increasing height of the snowsurface, but their location may be constrained from observations using radiative transfer modeling. Radial snowlines are not really accesible. Not only the ice abundance, but also inclination, settling, grain size distribution and disk mass have strong impact on the observed ice absorption features in disks. Relative changes in ice abundance can be inferred from observations only if the source structure is well constrained

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J. Sturm, M. McClure, J. Bergner, et. al.
Fri, 5 May 23
25/67

Comments: 18 pages, 12 figures, accepted for publication in Astronomy & Astrophysics

Instabilities in dusty non-isothermal proto-planetary discs [EPA]

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http://arxiv.org/abs/2305.02362


Protoplanetary discs (PPDs) can host a number of instabilities that may partake directly or indirectly in the process of planetesimal formation. These include the Vertical Shear Instability (VSI), Convective Overstability (COS), Streaming Instability (SI), and Dust Settling Instability (DSI), to name a few. Notably, the VSI and COS have mostly been studied in purely gaseous discs, while the SI and DSI have only been analyzed in isothermal discs. How these instabilities operate under more general conditions is therefore unclear. To this end, we devise a local model of a PPD describing a non-isothermal gas interacting with a single species of dust via drag forces. Using this, we find that dust drag sets minimum length scales below which the VSI and COS are suppressed. Similarly, we find that the SI can be suppressed on sufficiently small scales by the gas’ radial buoyancy if it cools on roughly a dynamical timescale. We show that the DSI can be effectively stabilized by vertical buoyancy, except at special radial and vertical length scales. We also find novel instabilities unique to a dusty, non-isothermal gas. These result in a dusty analog of the COS that operates in slowly cooled discs, and a dusty version of the VSI that is strongly enhanced by dust settling. We briefly discuss the possible implications of our results on planetesimal formation.

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M. Lehmann and M. Lin
Fri, 5 May 23
34/67

Comments: 40 pages, 26 figures

Non-detection of Helium in the Hot Jupiter WASP-48b [EPA]

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http://arxiv.org/abs/2305.02465


Hot Jupiters orbiting extremely close to their host star may experience atmospheric escape due to the large amounts of high-energy radiation they receive. Understanding the conditions under which this occurs is critical, as atmospheric escape is believed to be a driving factor in sculpting planetary populations. In recent years, the near-infrared 10833 \r{A} helium feature has been found to be a promising spectral signature of atmospheric escape. We use transmission spectroscopy to search for excess helium absorption in the extended atmosphere of WASP-48b, a hot Jupiter orbiting a slightly evolved, rapidly-rotating F star. The data were collected using the Habitable Zone Planet Finder spectrograph on the Hobby-Eberly Telescope. Observations were taken over the course of seven nights, from which we obtain three transits. No detectable helium absorption is seen, as absorption depth is measured to $-0.0025\pm0.0021$, or $1.2 \sigma$ from a null detection. This non-detection follows our current understanding of decreasing stellar activity (and thus high-energy radiation) with age. We use a 1D isothermal Parker wind model to compare with our observations and find our non-detection can best be explained with a low planetary mass-loss rate and high thermosphere temperature. We explore our results within the context of the full sample of helium detections and non-detections to date. Surprisingly, comparing helium absorption with the stellar activity index $\rm log\;R’_{HK}$ reveals a large spread in the correlation between these two factors, suggesting that there are additional parameters influencing the helium absorption strength.

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K. Bennett, S. Redfield, A. Oklopčić, et. al.
Fri, 5 May 23
46/67

Comments: 19 pages, 8 figures, 5 tables. Accepted for publication in AJ

No Evidence for Additional Planets at GJ 3470 from TESS and Archival Radial Velocities [EPA]

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http://arxiv.org/abs/2305.02551


The nearby M2 dwarf GJ 3470 has been the target of considerable interest after the discovery of a transiting short-period Neptune-sized planet. Recently, claims regarding the existence of additional transiting planets has gotten some attention, suggesting both the presence of a gas giant in the habitable zone, and that the system hosts a remarkable co-orbital gas giant configuration. We show that the existence of these three additional planets are readily amenable to testing with available data from both ground-based radial velocity data and space-based TESS photometry. A periodogram search of the available radial velocities show no compelling signals at the claimed periods, and the TESS photometry effectively rules out these planets assuming a transiting configuration. While it is doubtlessly possible that additional planets orbit GJ 3470, there is no evidence to date for their existence, and the available data conclusively rule out any planets similar to those considered in this text.

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T. Tarrants and A. Li
Fri, 5 May 23
54/67

Comments: N/A

Carbon dredge-up required to explain the Gaia white dwarf colour-magnitude bifurcation [SSA]

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http://arxiv.org/abs/2305.02827


The Gaia colour-magnitude diagram reveals a striking separation between hydrogen-atmosphere white dwarfs and their helium-atmosphere counterparts throughout a significant portion of the white dwarf cooling track. However, pure-helium atmospheres have Gaia magnitudes that are too close to the pure-hydrogen case to explain this bifurcation. To reproduce the observed split in the cooling sequence, it has been shown that trace amounts of hydrogen and/or metals must be present in the helium-dominated atmospheres of hydrogen-deficient white dwarfs. Yet, a complete explanation of the Gaia bifurcation that takes into account known constraints on the spectral evolution of white dwarfs has thus far not been proposed. In this work, we attempt to provide such a holistic explanation by performing population synthesis simulations coupled with state-of-the-art model atmospheres and evolutionary calculations that account for element transport in the envelopes of white dwarfs. By relying on empirically grounded assumptions, these simulations successfully reproduce the bifurcation. We show that the convective dredge-up of optically invisible traces of carbon from the deep interior is crucial to account for the observations. Neither the convective dilution/mixing of residual hydrogen nor the accretion of hydrogen or metals can be the dominant drivers of the bifurcation. Finally, we emphasize the importance of improving the equation of state of partially ionized carbon in warm dense helium, a key input for our predictions of the amount of dredged-up carbon.

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S. Blouin, A. Bédard and P. Tremblay
Fri, 5 May 23
57/67

Comments: Under review at MNRAS, submitted on 2023-03-15

The Shape of Jupiter and Saturn Based on Atmospheric Dynamics, Radio Occultations and Gravity Measurements [EPA]

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http://arxiv.org/abs/2305.02647


The shape of the two gas giants, Jupiter and Saturn, is determined primarily by their rotation rate, and interior density distribution. It is also affected by their zonal winds, causing an anomaly of O(10 km) at low latitudes. However, uncertainties in the observed cloud-level wind and the polar radius, translate to an uncertainty in the shape with the same order of magnitude. The Juno (Jupiter) and Cassini (Saturn) missions gave unprecedented accurate gravity measurements, constraining better the uncertainty in the wind structure. Using an accurate shape calculation, and a joint optimization, given both gravity and radio-occultation measurements, we calculate the possible range of dynamical height for both planets. We find that for Saturn there is an excellent match to the radio-occultation measurements, while at Jupiter such a match is not achieved. This may point to deviations from a barotropic flow above the cloud level, which might be tested with the forthcoming radio-occultation measurements by Juno.

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E. Galanti, Y. Kaspi and T. Guillot
Fri, 5 May 23
66/67

Comments: N/A

The Planetary Accretion Shock. III. Smoothing-free 2.5D simulations and calculation of H alpha emission [EPA]

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http://arxiv.org/abs/2305.01679


Surveys have looked for H alpha emission from accreting gas giants but found very few objects. Analyses of the detections and non-detections have assumed that the entire gas flow feeding the planet is in radial free-fall. However, hydrodynamical simulations suggest that this is far from reality. We calculate the H alpha emission from multidimensional accretion onto a gas giant, following the gas flow from Hill-sphere scales down to the circumplanetary disc (CPD) and the planetary surface. We perform azimuthally-symmetric radiation-hydrodynamics simulations around the planet and use modern tabulated gas and dust opacities. Crucially, contrasting with most previous simulations, we do not smooth the gravitational potential and do follow the flow down to the planetary surface, where grid cells are 0.01 Jupiter radii small radially. We find that only roughly one percent of the net gas inflow into the Hill sphere reaches directly the planet. As expected for ballistic infall trajectories, most of the gas falls at too large a distance on the CPD to generate H alpha. Including radiation transport removes the high-velocity sub-surface flow previously seen in hydrodynamics-only simulations, so that only the free planet surface and the inner regions of the CPD emit substantially H alpha. Unless magnetospheric accretion, which we neglect here, additionally produces H alpha, the corresponding H alpha production efficiency is much smaller than usually assumed, which needs to be taken into account when analysing (non-)detection statistics.

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G. Marleau, R. Kuiper, W. Béthune, et. al.
Thu, 4 May 23
1/60

Comments: Main text: 16 pages, 7 figures; appendices: 4 pages, 4 figures. Resubmitted on April 5th after first referee report, accepted at ApJ on April 19th

Viscosity contrasts in the Venus mantle from tidal deformations [EPA]

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http://arxiv.org/abs/2305.02278


The tidal deformations of a planet are often considered as markers of its inner structure. In this work, we use the tide excitations induced by the Sun on Venus for deciphering the nature of its internal layers. In using a Monte Carlo Random Exploration of the space of parameters describing the thickness, density and viscosity of 4 or 5 layer profiles, we were able to select models that can reproduce the observed mass, total moment of inertia, $k_2$ Love number and expected quality factor $Q$. Each model is assumed to have homogeneous layers with constant density, viscosity and rigidity. These models show significant contrasts in the viscosity between the upper mantle and the lower mantle. They also rather favor a S-free core and a slightly hotter lower mantle consistent with previous expectations.

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C. Saliby, A. Fienga, A. Briaud, et. al.
Thu, 4 May 23
3/60

Comments: Accepted for publication in Planetary and Space Sciences

An Interferometric SETI Observation of Kepler-111 b [GA]

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http://arxiv.org/abs/2305.02262


The application of Very Long Baseline Interferometry (VLBI) to the Search for Extraterrestrial Intelligence (SETI) has been limited to date, despite the technique offering many advantages over traditional single-dish SETI observations. In order to further develop interferometry for SETI, we used the European VLBI Network (EVN) at $21$~cm to observe potential secondary phase calibrators in the Kepler field. Unfortunately, no secondary calibrators were detected. However, a VLBA primary calibrator in the field, J1926+4441, offset only $\sim1.88’$ from a nearby exoplanet Kepler-111~b, was correlated with high temporal $\left(0.25 \ \rm{s}\right)$ and spectral $\left(16384 \times 488\ \rm{Hz \ channels}\right)$ resolution. During the analysis of the high-resolution data, we identified a spectral feature that was present in both the auto and cross-correlation data with a central frequency of $1420.424\pm0.0002$ MHz and a width of 0.25 MHz. We demonstrate that the feature in the cross-correlations is an artefact in the data, associated with a significant increase in each telescope’s noise figure due to the presence of \ion{H}{i} in the beam. This would typically go unnoticed in data correlated with standard spectral resolution. We flag (excluded from the subsequent analysis) these channels and phase rotate the data to the location of Kepler-111~b aided by the GAIA catalogue and search for signals with $\rm{SNR}>7$. At the time of our observations, we detect no transmitters with an Equivalent Isotropically Radiated Power (EIRP) > $\sim4\times10^{15}$ W.

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K. Wandia
Thu, 4 May 23
8/60

Comments: 11 pages, 12 figures

Timescales of Chaos in the Inner Solar System: Lyapunov Spectrum and Quasi-integrals of Motion [EPA]

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http://arxiv.org/abs/2305.01683


Numerical integrations of the Solar System reveal a remarkable stability of the orbits of the inner planets over billions of years, in spite of their chaotic variations characterized by a Lyapunov time of only 5 million years and the lack of integrals of motion able to constrain their dynamics. To open a window on such long-term behavior, we compute the entire Lyapunov spectrum of a forced secular model of the inner planets. We uncover a hierarchy of characteristic exponents that spans two orders of magnitude, manifesting a slow-fast dynamics with a broad separation of timescales. A systematic analysis of the Fourier harmonics of the Hamiltonian, based on computer algebra, reveals three symmetries that characterize the strongest resonances responsible for the orbital chaos. These symmetries are broken only by weak resonances, leading to the existence of quasi-integrals of motion that are shown to relate to the smallest Lyapunov exponents. A principal component analysis of the orbital solutions independently confirms that the quasi-integrals are among the slowest degrees of freedom of the dynamics. Strong evidence emerges that they effectively constrain the chaotic diffusion of the orbits, playing a crucial role in the statistical stability over the Solar System lifetime.

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F. Mogavero, N. Hoang and J. Laskar
Thu, 4 May 23
34/60

Comments: 24 pages, 11 figures. Published in Physical Review X

Power-2 limb-darkening coefficients for the $uvby$, $UBVRIJHK$, SDSS $ugriz$, Gaia, Kepler, TESS, and CHEOPS photometric systems II. PHOENIX spherically symmetric stellar atmosphere models [SSA]

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http://arxiv.org/abs/2305.01704


Multiple parametric limb-darkening laws have been presented, and there are many available sources of theoretical limb-darkening coefficients (LDCs) calculated using stellar model atmospheres. The power-2 limb-darkening law allows a very good representation of theoretically predicted intensity profiles, but few LDCs are available for this law from spherically symmetric model atmospheres. We therefore present such coefficients in this work. We computed LDCs for the space missions \textit{Gaia}, \textit{Kepler}, TESS, and CHEOPS and for the passbands $uvby$, $UBVRIJHK$, and SDSS $ugriz$, using the \textsc{phoenix-cond} spherical models. We adopted two methods to characterise the truncation point, which sets the limb of the star: the first (M1) uses the point where the derivative d$I(r)$/d$r$ is at its maximum where I(r) is the specific intensity as a function of the normalised radius r corresponding to $\mu_{\rm cri}$, and the second (M2) uses the midpoint between the point $\mu_{\rm cri}$ and the point located at $\mu_{\rm cri-1}$. The LDCs were computed adopting the Levenberg-Marquardt least-squares minimisation method, with a resolution of 900 equally spaced $\mu$ points, and covering 823 model atmospheres for a solar metallicity, effective temperatures of 2300 to 12000\,K, $\log g$ values from 0.0 to 6.0, and microturbulent velocities of 2\,km\,s$^{-1}$. As our previous calculations of LDCs using spherical models included only 100 $\mu$ points, we also updated the calculations for the four-parameter law for the passbands listed above, and compared them with those from the power-2 law. Comparisons between the quality of the fits provided by the power-2 and four-parameter laws show that the latter presents a lower merit function, $\chi^2$, than the former for both cases (M1 and M2). This is important when choosing the best approach for a particular science goal.

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A. Claret and J. Southworth
Thu, 4 May 23
40/60

Comments: N/A

Metallicity and age effects on lithium depletion in solar analogues [SSA]

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http://arxiv.org/abs/2305.01861


The lithium present in the photospheres of solar-type stars is transported to the inner parts by convection, reaching regions even somewhat below the convection zone, by non-standard transport mechanisms. In stars with deeper convective zones, this element can reach regions with temperatures sufficient enough to be destroyed, implying in a lower Li content. More metallic stars show a deepening of their convective zones, so they could deplete more Li in comparison with stars of lower metallicity. In order to verify this effect and its amplitude, we selected stars with ~1 M$_{\odot}$ and metallicities within a factor of two relative to the Sun. We studied a sample of 41 metal-rich and -poor solar analogues, and carried out a joint analysis with a sample of 77 solar twins from our previous work, resulting in a total sample of 118 stars covering the metallicity range -0.3 $\leq$ [Fe/H] $\leq$ +0.3 dex. We employed high-resolution (R = 115 000) and high-signal-to-noise ratio (S/N = 400-1000) HARPS spectra and determined the atmospheric parameters using a line-by-line differential analysis and the Li abundance through spectral synthesis. The ages and masses of the whole sample were improved by refining the isochronal method. We also investigated the impact of planets on Li. We found robust anticorrelations between Li abundance and both metallicity and age, with a significance above 10$\sigma$ in both cases. Our results agree qualitatively with theoretical predictions and are useful to constrain non-standard models of Li depletion, and to better understand transport and mixing mechanisms inside stars.

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G. Martos, J. Meléndez, A. Rathsam, et. al.
Thu, 4 May 23
44/60

Comments: 10 pages, 5 figures, 2 tables

Photosynthesis Under a Red Sun: Predicting the absorption characteristics of an extraterrestrial light-harvesting antenna [EPA]

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http://arxiv.org/abs/2305.02067


Here we discuss the feasibility of photosynthesis on Earth-like rocky planets in close orbit around ultra-cool red dwarf stars. Stars of this type have very limited emission in the \textit{photosynthetically active} region of the spectrum ($400 – 700$ nm), suggesting that they may not be able to support oxygenic photosynthesis. However, photoautotrophs on Earth frequently exploit very dim environments with the aid of highly structured and extremely efficient antenna systems. Moreover, the anoxygenic photosynthetic bacteria, which do not need to oxidize water to source electrons, can exploit far red and near infrared light. Here we apply a simple model of a photosynthetic antenna to a range of model stellar spectra, ranging from ultra-cool (2300 K) to Sun-like (5800 K). We assume that a photosynthetic organism will evolve an antenna that maximizes the rate of energy input while also minimizing fluctuations. The latter is the ‘noise cancelling’ principle recently reported by Arp et al. 2020. Applied to the Solar spectrum this predicts optimal antenna configurations in agreement with the chlorophyll Soret absorption bands. Applied to cooler stars, the optimal antenna peaks become redder with decreasing stellar temperature, crossing to the typical wavelength ranges associated with anoxygenic photoautotrophs at $\sim 3300$ K. Lastly, we compare the relative input power delivered by antennae of equivalent size around different stars and find that the predicted variation is within the same order of magnitude. We conclude that low-mass stars do not automatically present light-limiting conditions for photosynthesis but they may select for anoxygenic organisms.

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C. Duffy, G. Canchon, T. Haworth, et. al.
Thu, 4 May 23
47/60

Comments: Resubmitted to MNRAS

Wapiti: a data-driven approach to correct for systematics in RV data — Application to SPIRou data of the planet-hosting M dwarf GJ 251 [EPA]

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http://arxiv.org/abs/2305.02123


Context: Recent advances in the development of precise radial velocity (RV) instruments in the near-infrared (nIR) domain, such as SPIRou, have facilitated the study of M-type stars to more effectively characterize planetary systems. However, the nIR presents unique challenges in exoplanet detection due to various sources of planet-independent signals which can result in systematic errors in the RV data.
Aims: In order to address the challenges posed by the detection of exoplanetary systems around M-type stars using nIR observations, we introduce a new data-driven approach for correcting systematic errors in RV data. The effectiveness of this method is demonstrated through its application to the star GJ\,251.
Methods: Our proposed method, referred to as \texttt{Wapiti} (Weighted principAl comPonent analysIs reconsTructIon), uses a dataset of per-line RV time-series generated by the line-by-line (LBL) algorithm and employs a weighted principal component analysis (wPCA) to reconstruct the original RV time-series. A multi-step process is employed to determine the appropriate number of components, with the ultimate goal of subtracting the wPCA reconstruction of the per-line RV time-series from the original data in order to correct systematic errors.
Results: The application of \texttt{Wapiti} to GJ\,251 successfully eliminates spurious signals from the RV time-series and enables the first detection in the nIR of GJ\,251b, a known temperate super-Earth with an orbital period of 14.2 days. This demonstrates that, even when systematics in SPIRou data are unidentified, it is still possible to effectively address them and fully realize the instrument’s capability for exoplanet detection. Additionally, in contrast to the use of optical RVs, this detection did not require to filter out stellar activity, highlighting a key advantage of nIR RV measurements.

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M. Ould-Elhkim, C. Moutou, J. Donati, et. al.
Thu, 4 May 23
48/60

Comments: Submitted to A&A. For the publicly available Wapiti code, see this https URL

Schedule optimization for transiting exoplanet observations with NASA's Pandora SmallSat mission [IMA]

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http://arxiv.org/abs/2305.02285


Pandora is an upcoming NASA SmallSat mission that will observe transiting exoplanets to study their atmospheres and the variability of their host stars. Efficient mission planning is critical for maximizing the science achieved with the year-long primary mission. To this end, we have developed a scheduler based on a metaheuristic algorithm that is focused on tackling the unique challenges of time-constrained observing missions, like Pandora. Our scheduling algorithm combines a minimum transit requirement metric, which ensures we meet observational requirements, with a `quality’ metric that considers three factors to determine the scientific quality of each observation window around an exoplanet transit (defined as a visit). These three factors are: observing efficiency during a visit, the amount of the transit captured by the telescope during a visit, and how much of the transit captured is contaminated by a coincidental passing of the observatory through the South Atlantic Anomaly. The importance of each of these factors can be adjusted based on the needs or preferences of the science team. Utilizing this schedule optimizer, we develop and compare a few schedules with differing factor weights for the Pandora SmallSat mission, illustrating trade-offs that should be considered between the three quality factors. We also find that under all scenarios probed, Pandora will not only be able to achieve its observational requirements using the planets on the notional target list but will do so with significant time remaining for ancillary science.

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T. Foote, T. Barclay, C. Hedges, et. al.
Thu, 4 May 23
51/60

Comments: 35 pages, 7 figures. Submitted to JATIS, SPIE. Python code is available at: this https URL

Quantifying the Impact of the Dust Torque on the Migration of Low-mass Planets [EPA]

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http://arxiv.org/abs/2305.02140


Disk solids are critical in many planet formation processes, however, their effect on planet migration remains largely unexplored. Here we assess for the first time this important issue by building on the systematic measurements of dust torques on an embedded planet by Benitez-Llambay & Pessah (2018). Adopting standard models for the gaseous disk and its solid content, we quantify the impact of the dust torque for a wide range of conditions describing the disk/planet system. We show that the total torque can be positive and revert inward planet migration for planetary cores with $M_{\rm p} \lesssim 10 M_\oplus$. We compute formation tracks for low-mass embryos for conditions usually invoked when modeling planet formation processes. Our most important conclusion is that dust torques can have a significant impact on the migration and formation history of planetary embryos. The most important implications of our findings are: $\it{i})$ For nominal dust-to-gas mass ratios $\epsilon \simeq 0.01$, low-mass planets migrate outwards beyond the water ice-line if most of the mass in solids is in particles with Stokes numbers St $\simeq 0.1$. $\it{ii})$. For $\epsilon \gtrsim 0.02-0.05$, solids with small Stokes numbers, St $\simeq 0.01$, can play a dominant role if most of the mass is in those particles. $\it{iii})$ Dust torques have the potential to enable low-mass planetary cores formed in the inner disk to migrate outwards and act as the seed for massive planets at distances of tens of au.

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O. Guilera, P. Benitez-Llambay, M. Bertolami, et. al.
Thu, 4 May 23
53/60

Comments: Paper submitted to ApJ after minor corrections required. Feedback from the community is welcome

The maximum accretion rate of a protoplanet: how fast can runaway be? [EPA]

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http://arxiv.org/abs/2305.01684


The hunt is on for dozens of protoplanets hypothesised to reside in protoplanetary discs with imaged gaps. How bright these planets are, and what they will grow to become, depend on their accretion rates, which may be in the runaway regime. Using 3D global simulations we calculate maximum gas accretion rates for planet masses $M_{\rm p}$ from 1$\,M_{\oplus}$ to $10\,M_{\rm J}$. When the planet is small enough to be fully embedded in the disc, with a Bondi radius $r_{\rm Bondi}$ smaller than the disc’s scale height $H_{\rm p}$ — such planets have thermal mass parameters $q_{\rm th} \equiv (M_{\rm p}/M_{\star}) / (H_{\rm p}/R_{\rm p})^3 \lesssim 0.5$, for host stellar mass $M_{\star}$ and orbital radius $R_{\rm p}$ — the maximum accretion rate follows a Bondi scaling, with $\max \dot{M}{\rm p} \propto M{\rm p}^2 / (H_{\rm p}/R_{\rm p})^3$. For more massive planets with $0.5 \lesssim q_{\rm th} \lesssim 10$, the Hill sphere replaces the Bondi sphere as the gravitational sphere of influence, and $\max \dot{M}{\rm p} \propto M{\rm p}^1$, with no dependence on $H_{\rm p}/R_{\rm p}$. In the strongly superthermal limit when $q_{\rm th} \gtrsim 10$, the Hill sphere pops well out of the disc and $\max \dot{M}{\rm p} \propto M{\rm p}^{2/3} (H_{\rm p}/R_{\rm p})^1$. Applied to the two confirmed protoplanets PDS 70b and c, our numerically calibrated maximum accretion rates imply their Jupiter-like masses may increase by up to a factor of $\sim$2 before their parent disc dissipates.

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N. Choksi, E. Chiang, J. Fung, et. al.
Thu, 4 May 23
54/60

Comments: Submitted to MNRAS

Joint Modeling of Radial Velocities and Photometry with a Gaussian Process Framework [EPA]

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http://arxiv.org/abs/2305.00988


Developments in the stability of modern spectrographs have led to extremely precise instrumental radial velocity (RV) measurements. For most stars, the detection limit of planetary companions with these instruments is expected to be dominated by astrophysical noise sources such as starspots. Correlated signals caused by rotationally-modulated starspots can obscure or mimic the Doppler shifts induced by even the closest, most massive planets. This is especially true for young, magnetically active stars where stellar activity can cause fluctuation amplitudes of $\gtrsim$0.1 mag in brightness and $\gtrsim$100 m s$^{-1}$ in RV semi-amplitudes. Techniques that can mitigate these effects and increase our sensitivity to young planets are critical to improving our understanding of the evolution of planetary systems. Gaussian processes (GPs) have been successfully employed to model and constrain activity signals in individual cases. However, a principled approach of this technique, specifically for the joint modeling of photometry and RVs, has not yet been developed. In this work, we present a GP framework to simultaneously model stellar activity signals in photometry and RVs that can be used to investigate the relationship between both time series. Our method, inspired by the $\textit{FF}^\prime$ framework of (Aigrain et al. 2012), models spot-driven activity signals as the linear combinations of two independent latent GPs and their time derivatives. We also simulate time series affected by starspots by extending the $\texttt{starry}$ software (Luger et al. 2019) to incorporate time evolution of stellar features. Using these synthetic datasets, we show that our method can predict spot-driven RV variations with greater accuracy than other GP approaches.

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Q. Tran, M. Bedell, D. Foreman-Mackey, et. al.
Wed, 3 May 23
12/67

Comments: 19 pages, 10 figures

Revised Properties and Dynamical History for the HD 17156 System [EPA]

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http://arxiv.org/abs/2305.01000


From the thousands of known exoplanets, those that transit bright host stars provide the greatest accessibility toward detailed system characterization. The first known such planets were generally discovered using the radial velocity technique, then later found to transit. HD 17156b is particularly notable among these initial discoveries because it diverged from the typical hot Jupiter population, occupying a 21.2 day eccentric ($e = 0.68$) orbit, offering preliminary insights into the evolution of planets in extreme orbits. Here we present new data for this system, including ground and space-based photometry, radial velocities, and speckle imaging, that further constrain the system properties and stellar/planetary multiplicity. These data include photometry from the Transiting Exoplanet Survey Satellite (TESS) that cover five transits of the known planet. We show that the system does not harbor any additional giant planets interior to 10 AU. The lack of stellar companions and the age of the system indicate that the eccentricity of the known planet may have resulted from a previous planet-planet scattering event. We provide the results from dynamical simulations that suggest possible properties of an additional planet that culminated in ejection from the system, leaving a legacy of the observed high eccentricity for HD 17156b.

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S. Kane, M. Hill, P. Dalba, et. al.
Wed, 3 May 23
13/67

Comments: 15 pages, 7 figures, accepted for publication in the Astronomical Journal

Interior-atmosphere modelling to assess the observability of rocky planets with JWST [EPA]

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http://arxiv.org/abs/2305.01250


Super-Earths present compositions dominated by refractory materials. However, there is a degeneracy in their interior structure between a planet with no atmosphere and a small Fe content, and a planet with a thin atmosphere and a higher core mass fraction. To break this degeneracy, atmospheric characterization observations are required. We present a self-consistent interior-atmosphere model to constrain the volatile mass fraction, surface pressure, and temperature of rocky planets with water and CO2 atmospheres. These parameters obtained in our analysis can then be used to predict observations in emission spectroscopy and photometry with JWST, which can determine the presence of an atmosphere, and if present, its composition. To obtain the bolometric emission and Bond albedo for an atmosphere in radiative-convective equilibrium, we present the k-uncorrelated approximation for fast computations within our retrieval on planetary mass, radius and host stellar abundances. For the generation of emission spectra, we use our k-correlated atmospheric model. An adaptive MCMC is used for an efficient sampling of the parameter space at low volatile mass fractions. We show how to use our modelling approach to predict observations with JWST for TRAPPIST-1 c and 55 Cancri e. TRAPPIST-1 c’s most likely scenario is a bare surface, although the presence of an atmosphere cannot be ruled out. If the emission in the MIRI F1500 filter is 731 ppm or higher, there would be a water-rich atmosphere. For fluxes between 730 and 400 ppm, no atmosphere is present, while low emission fluxes (300 ppm) indicate a CO2-dominated atmosphere. In the case of 55 Cancri e, a combined spectrum with NIRCam and MIRI LRS may present high uncertainties at wavelengths between 3 and 3.7 $\mu$m. However, this does not affect the identification of H2O and CO2 because they do not present spectral features in this wavelength range.

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L. Acuna, M. Deleuil and O. Mousis
Wed, 3 May 23
16/67

Comments: 15 pages, 9 figures. Accepted for publication in A&A

Using planet migration and dust drift to weigh protoplanetary discs [EPA]

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http://arxiv.org/abs/2305.01493


ALMA has spatially resolved over 200 annular structures in protoplanetary discs, many of which are suggestive of the presence of planets. Constraining the mass of these putative planets is quite degenerate for it depends on the disc physical properties, and for simplicity a steady-state is often assumed whereby the planet position is kept fixed and there is a constant source of dust at the outer edge of the disc. Here we argue against this approach by demonstrating how the planet and dust dynamics can lift degeneracies of such steady-state models. We take main disc parameters from the well-known protoplanetary disc HD 163296 with a suspected planet at $R\approx 86$~au as an example. By running gas and dust hydrodynamical simulations post-processed with dust radiative transfer calculations, we first find steady-state disc and planet parameters that reproduce ALMA continuum observations fairly well. For the same disc mass, but now allowing the planet to migrate in the simulation, we find that the planet undergoes runaway migration and reaches the inner disc in $\sim 0.2$ Myr. Further, decreasing the disc mass slows down planet migration, but it then also increases the dust’s radial drift, thereby depleting the disc dust faster. We find that the opposing constraints of planet migration and dust drift require the disc mass to be at most $0.025~\msun$, must less massive than previously estimated, and for the dust to be porous rather than compact. We propose that similar analysis should be extended to other sources with suspected planetary companions.

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Y. Wu, C. Baruteau and S. Nayakshin
Wed, 3 May 23
25/67

Comments: 15 pages, 9 figures, resubmitted to MNRAS, version addressing referee’s comments

Performance of chaos diagnostics based on Lagrangian descriptors. Application to the 4D standard map [EPA]

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http://arxiv.org/abs/2305.00978


We investigate the ability of simple diagnostics based on Lagrangian descriptor (LD) computations of initially nearby orbits to detect chaos in conservative dynamical systems with phase space dimensionality higher than two. In particular, we consider the recently introduced methods of the difference ($D_L^n$) and the ratio ($R_L^n$) of the LDs of neighboring orbits, as well as a quantity ($S_L^n$) related to the finite-difference second spatial derivative of the LDs, and use them to determine the chaotic or regular nature of ensembles of orbits of a prototypical area-preserving map model, the 4-dimensional (4D) symplectic standard map. Using the distributions of the indices’ values we determine appropriate thresholds to discriminate between regular and chaotic orbits, and compare the obtained characterization against that achieved by the Smaller Alignment Index (SALI) method of chaos detection, by recording the percentage agreement $P_A$ between the two classifications. We study the influence of various factors on the performance of these indices, and show that the increase of the final number of orbit iterations T and the order n of the indices (i.e. the dimensionality of the space where the considered nearby orbits lie), as well as the decrease of the distance $\sigma$ of neighboring orbits, increase the $P_A$ values along with the required computational effort. Balancing between these two factors we find appropriate T, n and $\sigma$ values, which allow the efficient use of the $D_L^n$, $R_L^n$ and $S_L^n$ indices as short time and computationally cheap chaos diagnostics achieving $P_A \gtrsim 90 \%$, with $D_L^n$ and $S_L^n$ having larger $P_A$ values than $R_L^n$. Our results show that the three LDs-based indices perform better for systems with large percentages of chaotic orbits.

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S. Zimper, A. Ngapasare, M. Hillebrand, et. al.
Wed, 3 May 23
27/67

Comments: N/A

Theoretical tidal evolution constants for stellar models from the pre-main sequence to the white dwarf stage Apsidal motion constants, moment of inertia, and gravitational potential energy [SSA]

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http://arxiv.org/abs/2305.01627


One of the most reliable means of studying the stellar interior is through the apsidal motion in double line eclipsing binary systems since these systems present errors in masses, radii, and effective temperatures of only a few per cent. On the other hand, the theoretical values of the apsidal motion to be compared with the observed values depend on the stellar masses of the components and more strongly on their radii (fifth power).The main objective of this work is to make available grids of evolutionary stellar models that, in addition to the traditional parameters (e.g. age, mass, log g, T${\rm eff}$), also contain the necessary parameters for the theoretical study of apsidal motion and tidal evolution. This information is useful for the study of the apsidal motion in eclipsing binaries and their tidal evolution, and can also be used for the same purpose in exoplanetary systems. All models were computed using the MESA package. We consider core overshooting for models with masses $\ge$ 1.2 M$\odot$. For the amount of core overshooting we adopted a recent relationship for mass $\times$ core overshooting. We adopted for the mixing-length parameter $\alpha_{\rm MLT}$ the value 1.84 (the solar-calibrated value). Mass loss was taken into account in two evolutionary phases. The models were followed from the pre-main sequence phase to the white dwarf (WD) stage.The evolutionary models containing age,luminosity, log g, and Teff, as well as the first three harmonics of the internal stellar structure (k$_2$, k$_3$, and k$_4$), the radius of gyration $\beta$ y, and the dimensionless variable $\alpha$, related to gravitational potential energy, are presented in 69 tables covering three chemical compositions: [Fe/H] = -0.50, 0.00, and 0.50. Additional models with different input physics are available.

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A. Claret
Wed, 3 May 23
51/67

Comments: N/A

Coma environment of comet C/2017 K2 around the water ice sublimation boundary observed with VLT/MUSE [EPA]

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http://arxiv.org/abs/2305.01385


We report a new imaging spectroscopic observation of Oort-cloud comet C/2017 K2 (hereafter K2) on its way to perihelion at 2.53 au, around a heliocentric distance where H2O ice begins to play a key role in comet activation. Normalized reflectances over 6 500–8 500 AA for its inner and outer comae are 9.7+/-0.5 and 7.2+/-0.3 % (10^3 AA)^-1, respectively, the latter being consistent with the slope observed when the comet was beyond the orbit of Saturn. The dust coma at the time of observation appears to contain three distinct populations: mm-sized chunks prevailing at <~10^3 km; a 10^5-km steady-state dust envelope; and fresh anti-sunward jet particles. the dust chunks dominate the continuum signal and are distributed over a similar radial distance scale as the coma region with redder dust than nearby. they also appear to be co-spatial with OI1D, suggesting that the chunks may accommodate H2O ice with a fraction (>~1 %) of refractory materials. The jet particles do not colocate with any gas species detected. The outer coma spectrum contains three significant emissions from C2(0,0) Swan band, OI1D, and CN(1,0 red band, with an overall deficiency in NH2. Assuming that all OI1D flux results from H2O dissociation, we compute an upper limit on the water production rate Q_H2O of ~7 x 10^28 molec s^-1 (with an uncertainty of a factor of two). the production ratio log[Q_C2/Q_CN] of K2 suggests that the comet has typical carbon-chain composition, with the value potentially changing with distance from the Sun. Our observations suggest that water ice-containing dust chunks (>0.1 mm) near K2’s nucleus emitted beyond 4 au may be responsible for its very low gas rotational temperature and the discrepancy between its optical and infrared lights reported at similar heliocentric distances.

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Y. Kwon, C. Opitom and M. Lippi
Wed, 3 May 23
53/67

Comments: Accepted for publication in Astronomy & Astrophysics

Lunar Mantle Structure and Composition Inferred From Apollo 12 – Explorer 35 Electromagnetic Sounding [EPA]

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http://arxiv.org/abs/2305.01462


Constraints on the interior structure of the Moon have been derived from its inductive response, principally as measured by the magnetic transfer function (TF) between the distantly orbiting Explorer 35 satellite and the Apollo 12 surface station. The most successful prior studies used a dataset 0.01-1 mHz, so the lunar response could be modeled as a simple dipole. However, earlier efforts also produced transfer functions up to 40 mHz. The smaller electromagnetic skin depth at higher frequency would better resolve the uppermost mantle – where key information about primitive lunar evolution may still be preserved – but requires a multipole treatment.
I compute new profiles of electrical conductivity vs depth using both the low-frequency and the full-bandwidth ranges of published Apollo-Explorer TFs. I derive temperature profiles at depths >400 km (<1 mHz) consistent with conductive heat loss and expectations of the iron (and possibly water) content of the mantle. The near-constant iron fraction (Mg# 81 +/- 7) implies either efficient mixing, due to now-defunct convection or perhaps incomplete overturn of gravitationally unstable cumulates following crystallization of the magma ocean.
In contrast, the full-bandwidth analysis produced a different conductivity profile that could not be realistically matched by conduction, convection, partial melting, or simple considerations of lateral heterogeneity. I conclude that the TF method at the Moon is unreliable >>1 mHz. Future EM sounding using the magnetotelluric method can operate up to 100s Hz and is largely insensitive to multipole effects, resolving structure to 100 km or less.

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R. Grimm
Wed, 3 May 23
57/67

Comments: N/A

Enabling discovery of solar system objects in large alert data streams [EPA]

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http://arxiv.org/abs/2305.01123


With the advent of large-scale astronomical surveys such as the Zwicky Transient Facility (ZTF), the number of alerts generated by transient, variable and moving astronomical objects is growing rapidly, reaching millions per night. Concerning solar system minor planets, their identification requires linking the alerts of many observations over a potentially large time, leading to a very large combinatorial number. This work aims to identify new candidates for solar system objects from massive alert data streams produced by large-scale surveys, such as the ZTF and the Vera C. Rubin Observatory’s Legacy Survey of Space and Time. Our analysis used the Fink alert broker capabilities to reduce the 111,275,131 processed alerts from ZTF between November 2019 and December 2022 to only 389,530 new solar system alert candidates over the same period. We then implemented a linking algorithm, Fink-FAT, to create real-time trajectory candidates from alert data and extract orbital parameters. The analysis was validated on ZTF alert packets linked to confirmed solar system objects from the Minor Planet Center database. Finally, the results were confronted against follow-up observations. Between November 2019 and December 2022, Fink-FAT extracted 327 new orbits from solar system object candidates at the time of the observations, over which 65 were still unreported in the MPC database as of March 2023. After two late follow-up observation campaigns of six orbit candidates, four were associated with known solar system minor planets, and two remain unknown. Fink-FAT is deployed in the Fink broker and successfully analyzes in real time the alert data from the ZTF survey by regularly extracting new candidates for solar system objects. Our scalability tests also show that Fink-FAT can handle the even larger volume of alert data that the Rubin Observatory will send.

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R. Montagner, J. Peloton, B. Carry, et. al.
Wed, 3 May 23
58/67

Comments: submitted to A&A

M giants with IGRINS I. Stellar parameters and $α$-abundance trends of the solar neighborhood population [SSA]

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http://arxiv.org/abs/2305.00486


Cool stars, such as M giants, can only be analysed in the near-infrared (NIR) regime due to the ubiquitous TiO features in optical spectra of stars with Teff < 4000 K. In dust obscured regions, like the inner bulge and Galactic Center, the intrinsically bright M giants observed in the NIR is an optimal option to determine their stellar abundances. Due to uncertainties in photometric methods, a method to determine the stellar parameters for M giants from the NIR spectra themselves is needed.
We have carried out new observations of 44 M giant stars (also in APOGEE DR17) with IGRINS (R=45,000) mounted on the Gemini South telescope. We also obtained HK band IGRINS spectra of six nearby well-studied M giants from the IGRINS spectral library. Using this sample, we have developed a method to determine the stellar parameters for M giants from the NIR spectra by spectral synthesis using SME. The method is validated using the six nearby well-studied M-giants. We demonstrate the accuracy and precision by determining stellar parameters and $\alpha$-element trends versus metallicity for solar neighbourhood M giants.
The effective temperatures that we derive (tested for 3400$\lesssim$ Teff $\lesssim$4000\,K) agree excellently with the six nearby M giants which indicates that the accuracy is indeed high. For the 43 solar neighborhood M giants, our Teff, logg, [Fe/H], $\xi_\mathrm{micro}$, [C/Fe], [N/Fe], and [O/Fe] are in unison with APOGEE with mean differences and scatter (our method – APOGEE) of -67$\pm$33 K, -0.31$\pm$0.15 dex, 0.02$\pm$0.05 dex, 0.22$\pm$0.13 km/s, -0.05$\pm$0.06 dex, 0.06$\pm$0.06 dex, and 0.02$\pm$0.09 dex, respectively. The $\alpha$-element trends versus metallicity for Mg, Si, Ca and Ti are consistent with both APOGEE DR17 trends for the same stars as well as with the GILD optical trends. We also find clear enhancement in abundances for thick disc stars.

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G. Nandakumar, N. Ryde, L. Casagrande, et. al.
Tue, 2 May 23
6/57

Comments: 27 Pages including appendix of 10 pages, 15 figures, Accepted for publication in A&A

Formation of Gaps in Self-gravitating Debris Disks by Secular Resonance in a Single-planet System. II. Towards a Self-consistent Model [EPA]

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http://arxiv.org/abs/2305.00951


High-resolution observations of several debris disks reveal structures such as gaps and spirals, suggestive of gravitational perturbations induced by underlying planets. Most existing studies of planet–debris disk interactions ignore the gravity of the disk, treating it as a reservoir of massless planetesimals. In this paper, we continue our investigation into the long-term interaction between a single eccentric planet and an external, massive debris disk. Building upon our previous work, here we consider not only the axisymmetric component of the disk’s gravitational potential, but also the non-axisymmetric torque that the disk exerts on the planet (ignoring for now only the non-axisymmetric component of the disk \textit{self}-gravity). To this goal, we develop and test a semi-analytic `$N$-ring’ framework that is based on a generalized (softened) version of the classical Laplace–Lagrange secular theory. Using this tool, we demonstrate that even when the disk is less massive than the planet, not only can a secular resonance be established within the disk that leads to the formation of a wide non-axisymmetric gap (akin to those observed in HD 107146, HD 92945, and HD 206893), but that the very same resonance also damps the planetary eccentricity via a process known as resonant friction. We also develop analytic understanding of these findings, finding good quantitative agreement with the outcomes of the $N$-ring calculations. Our results may be used to infer both the dynamical masses of gapped debris disks and the dynamical history of the planets interior to them, as we exemplify for HD 206893.

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A. Sefilian, R. Rafikov and M. Wyatt
Tue, 2 May 23
11/57

Comments: Submitted to AAS Journals: 33 Pages (including 7 pages of Appendices), 15 Figures, 1 Table, 3 Animations (see Ancillary files). Comments are welcome

Star-Planet Interaction at radio wavelengths in YZ Ceti: Inferring planetary magnetic field [EPA]

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http://arxiv.org/abs/2305.00809


In exoplanetary systems, the interaction between the central star and the planet can trigger Auroral Radio Emission (ARE), due to the Electron Cyclotron Maser mechanism. The high brightness temperature of this emission makes it visible at large distances, opening new opportunities to study exoplanets and to search for favourable conditions for the development of extra-terrestrial life, as magnetic fields act as a shield that protects life against external particles and influences the evolution of the planetary atmospheres. In the last few years, we started an observational campaign to observe a sample of nearby M-type stars known to host exoplanets with the aim to detect ARE. We observed YZ Ceti with the upgraded Giant Metrewave Radio Telescope (uGMRT) in band 4 (550-900 MHz) nine times over a period of five months. We detected radio emission four times, two of which with high degree of circular polarization. With statistical considerations we exclude the possibility of flares due to stellar magnetic activity. Instead, when folding the detections to the orbital phase of the closest planet YZ Cet b, they are at positions where we would expect ARE due to star-planet interaction (SPI) in sub-Alfvenic regime. With a degree of confidence higher than 4.37 sigma, YZ Cet is the first extrasolar systems with confirmed SPI at radio wavelengths. Modelling the ARE, we estimate a magnetic field for the star of about 2.4 kG and we find that the planet must have a magnetosphere. The lower limit for the polar magnetic field of the planet is 0.4 G.

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C. Trigilio, A. Biswas, P. Leto, et. al.
Tue, 2 May 23
13/57

Comments: 11 pages, 7 figures, submitted to ApJ Letters in March 2023

SHAMPOO: A stochastic model for tracking dust particles under the influence of non-local disk processes [EPA]

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http://arxiv.org/abs/2305.00861


The abundances of CHNOS are crucial for the composition of planets. At the onset of planet formation, large amounts of these elements are stored in ices on dust grains in planet-forming disks. The evolution of this ice is affected by dynamical transport, collisional processes, and the formation and sublimation of ice. We aim to constrain the disk regions where these processes are fully coupled, and develop a flexible modelling approach that is able to predict the effects of these processes acting simultaneously on the CHNOS budgets of the dust in these regions. We compared timescales associated with these disk processes to constrain the disk regions where this approach is necessary, and developed the SHAMPOO code, which tracks the CHNOS abundances in the ice mantle of a single monomer dust particle, embedded in a larger aggregate and undergoing these processes simultaneously. The adsorption and photodesorption of monomer ices depend on the depth of the monomer in the aggregate. We investigated the effect of fragmentation velocity and aggregate filling factor on the amount of ice on monomers residing at r = 10 AU. The locations where disk processes are fully coupled depend on both grain size and ice species. Monomers embedded in aggregates with fragmentation velocities of 1 m/s are able to undergo adsorption and photodesorption more often compared to a fragmentation velocity of 5 m/s or 10 m/s. Aggregates with a filling factor of $10^{-3}$ are able to accumulate ice 22 times faster on average than aggregates with a filling factor of 1. As different grain sizes are coupled through collisions and the grain ice consists of multiple ice species, it is difficult to isolate the locations where disk processes are fully coupled, necessitating the development of the SHAMPOO code. The processing of ice may not be spatially limited to dust aggregate surfaces for either fragile or porous aggregates.

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M. Oosterloo, I. Kamp, W. Westrenen, et. al.
Tue, 2 May 23
22/57

Comments: 30 pages, 24 figures, 4 tables, to appear in Astronomy & Astrophysics

On the radial distribution of giant exoplanets at Solar System scales [EPA]

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http://arxiv.org/abs/2305.00047


Context. Giant planets play a major role in multiple planetary systems. Knowing their demographics is important to test their overall impact on planetary systems formation. It is also important to test their formation processes. Recently, three radial velocity surveys have established radial distributions of giant planets. All show a steep increase up to 1-3 au, and two suggest a decrease beyond. Aims. We aim at understanding the limitations associated with the characterization of long-period giant radial velocity planets, and to estimate their impact on the radial distribution of these planets. Methods. We revisit the results obtained by two major surveys that derived such radial distributions, using the RV data available at the time of the surveys as well as, whenever possible, new data. Results. We show that the radial distributions published beyond (5-8 au) are not secure. More precisely, the decrease of the radial distribution beyond the peak at 1-3 au is not confirmed.

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A. Lagrange, F. Philipot, P. Rubini, et. al.
Tue, 2 May 23
32/57

Comments: 26 pages, 20 figures, 2 tables

DREAM II. The spin-orbit angle distribution of close-in exoplanets under the lens of tides [EPA]

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http://arxiv.org/abs/2305.00829


The spin-orbit angle, or obliquity, is a powerful observational marker that allows us to access the dynamical history of exoplanetary systems. Here, we have examined the distribution of spin-orbit angles for close-in exoplanets and put it in a statistical context of tidal interactions between planets and their stars. We confirm the observed trends between the obliquity and physical quantities directly connected to tides, namely the stellar effective temperature, the planet-to-star mass ratio, and the scaled orbital distance. We further devised a tidal efficiency factor combining critical parameters that control the strength of tidal effects and used it to corroborate the strong link between the spin-orbit angle distribution and tidal interactions. In particular, we developed a readily usable formula to estimate the probability that a system is misaligned, which will prove useful in global population studies. By building a robust statistical framework, we reconstructed the distribution of the three-dimensional spin-orbit angles, allowing for a sample of nearly 200 true obliquities to be analyzed for the first time. This realistic distribution maintains the sky-projected trends, and additionally hints toward a striking pileup of truly aligned systems. The comparison between the full population and a pristine subsample unaffected by tidal interactions suggests that perpendicular architectures are resilient toward tidal realignment, providing evidence that orbital misalignments are sculpted by disruptive dynamical processes that preferentially lead to polar orbits. On the other hand, star-planet interactions seem to efficiently realign or quench the formation of any tilted configuration other than for polar orbits, and in particular for antialigned orbits.

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O. Attia, V. Bourrier, J. Delisle, et. al.
Tue, 2 May 23
36/57

Comments: Accepted in A&A

Stellar pulsations interfering with the transit light curve: configurations with false positive misalignment [EPA]

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http://arxiv.org/abs/2305.00440


Asymmetric features in exoplanet transit light curves are often interpreted as a gravity darkening effect especially if there is spectroscopic evidence of a spin-orbit misalignment. Since other processes can also lead to light curve asymmetries this may lead to inaccurate gravity darkening parameters. Here we investigate the case of non-radial pulsations as possible sources of asymmetry and likely source of misinterpreted parameters through simulations. We obtained a series of simulated transit light curves of a hypothetical exoplanet-star system: a host star with no gravity darkening exhibiting small amplitude pulsations, and a typical hot Jupiter in a circular, edge-on orbit. A number of scenarios of pulsations of various amplitudes were considered, and a proper account of the obscuring effect of transits on all the surface intensity components was made. The magnitude of amplitude and phase modulations of nonradial pulsations during transits was also also investigated. We then fitted both a non-gravity-darkened, and a gravity-darkened, free spin-orbit axis model on the data. The Akaike and Bayesian Information Criteria were used for an objective selection of the most plausible model. We then explored the dependence of the parameter deviations on the pulsation properties, in order to identify configurations that can lead to falsely misaligned solutions. Low-amplitude pulsations in general do not affect the determination of the system parameters beyond their noise nature. However, frequencies close to multiples of the orbital frequency are found to cause distortions leading to solutions with a side tilted stellar rotational axis, they are therefore preferable to clean beforehand for the sake of a correct analysis. Additionally, for cases with higher-amplitude pulsations, it is recommended to pre-process and clean the pulsations before analysis.

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A. Bókon, S. Kálmán, I. Bíró, et. al.
Tue, 2 May 23
37/57

Comments: Accepted in A&A on 24 April 2023, 14 pages, 10 figures

Small Planets Around Cool Dwarfs: Enhanced Formation Efficiency of Super-Earths around M dwarfs [EPA]

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http://arxiv.org/abs/2305.00803


Current measurements of planet population as a function of stellar mass show three seemingly contradictory signatures: close-in super-Earths are more prevalent around M dwarfs than FGK dwarfs; inner super-Earths are correlated with outer giants; and outer giants are less common around M dwarfs than FGK dwarfs. Here, we build a simple framework that combines the theory of pebble accretion with the measurements of dust masses in protoplanetary disks to reconcile all three observations. First, we show that cooler stars are more efficient at converting pebbles into planetary cores at short orbital periods. Second, when disks are massive enough to nucleate a heavy core at 5 AU, more than enough dust can drift in to assemble inner planets, establishing the correlation between inner planets and outer giants. Finally, while stars of varying masses are similarly capable of converting pebbles into cores at long orbital periods, hotter stars are much more likely to harbor more massive dust disks so that the giant planet occurrence rate rises around hotter stars. Our results are valid over a wide range of parameter space for a disk accretion rate that follows $\dot{M}\star \sim 10^{-8}\,M\odot\,{\rm yr}^{-1}(M_\star/M_\odot)^2$. We predict a decline in mini-Neptune population (but not necessarily terrestrial planets) around stars lighter than $\sim 0.3-0.5 \, M_\odot$. Cold giants ($\gtrsim$5 AU), if they exist, should remain correlated with inner planets even around lower mass stars.

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Y. Chachan and E. Lee
Tue, 2 May 23
38/57

Comments: submitted to AAS journals, comments welcome

High Tide or Riptide on the Cosmic Shoreline? A Water-Rich Atmosphere or Stellar Contamination for the Warm Super-Earth GJ~486b from JWST Observations [EPA]

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http://arxiv.org/abs/2305.00868


Planets orbiting M-dwarf stars are prime targets in the search for rocky exoplanet atmospheres. The small size of M dwarfs renders their planets exceptional targets for transmission spectroscopy, facilitating atmospheric characterization. However, it remains unknown whether their host stars’ highly variable extreme-UV radiation environments allow atmospheres to persist. With JWST, we have begun to determine whether or not the most favorable rocky worlds orbiting M dwarfs have detectable atmospheres. Here, we present a 2.8-5.2 micron JWST NIRSpec/G395H transmission spectrum of the warm (700 K, 40.3x Earth’s insolation) super-Earth GJ 486b (1.3 R${\oplus}$ and 3.0 M${\oplus}$). The measured spectrum from our two transits of GJ 486b deviates from a flat line at 2.2 – 3.3 $\sigma$, based on three independent reductions. Through a combination of forward and retrieval models, we determine that GJ 486b either has a water-rich atmosphere (with the most stringent constraint on the retrieved water abundance of H2O > 10% to 2$\sigma$) or the transmission spectrum is contaminated by water present in cool unocculted starspots. We also find that the measured stellar spectrum is best fit by a stellar model with cool starspots and hot faculae. While both retrieval scenarios provide equal quality fits ($\chi^2_\nu$ = 1.0) to our NIRSpec/G395H observations, shorter wavelength observations can break this degeneracy and reveal if GJ 486b sustains a water-rich atmosphere.

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S. Moran, K. Stevenson, D. Sing, et. al.
Tue, 2 May 23
41/57

Comments: 18 pages, 7 figures, 5 tables. Accepted in ApJ Letters. Co-First Authors

(130) Elektra Delta — on the stability of the new third moonlet [EPA]

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http://arxiv.org/abs/2304.14967


The aim of this work is to verify the stability of the proposed orbital solutions for the third moonlet (Delta) taking into account a realistic gravitational potential for the central body of the quadruple system (Alpha). We also aim to estimate the location and size of a stability region inside the orbit of Gamma. First, we created a set of test particles with intervals of semi-major axis, eccentricities, and inclinations that covers the region interior to the orbit of Gamma, including the proposed orbit of Delta and a wide region around it. We considered three different models for the gravitational potential of Alpha: irregular polyhedron, ellipsoidal body and oblate body. For a second scenario, Delta was considered a massive spherical body and Alpha an irregular polyhedron. Beta and Gamma were assumed as spherical massive bodies in both scenarios. The simulations showed that a large region of space is almost fully stable only when Alpha was modeled as simply as an oblate body. For the scenario with Delta as a massive body, the results did not change from those as massless particles. Beta and Gamma do not play any relevant role in the dynamics of particles interior to the orbit of Gamma. Delta’s predicted orbital elements are fully unstable and far from the nearest stable region. The primary instability source is Alpha’s elongated shape. Therefore, in the determination of the orbital elements of Delta, it must be taken into account the gravitational potential of Alpha assuming, at least, an ellipsoidal shape.

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G. Valvano, R. Oliveira, O. Winter, et. al.
Mon, 1 May 23
12/51

Comments: N/A

The Io, Europa and Ganymede auroral footprints at Jupiter in the ultraviolet: positions and equatorial lead angles [EPA]

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http://arxiv.org/abs/2304.14949


Jupiter’s satellite auroral footprints are a consequence of the interaction between the Jovian magnetic field with co-rotating iogenic plasma and the Galilean moons. The disturbances created near the moons propagate as Alfv\’en waves along the magnetic field lines. The position of the moons is therefore “Alfv\’enically” connected to their respective auroral footprint. The angular separation from the instantaneous magnetic footprint can be estimated by the so-called lead angle. That lead angle varies periodically as a function of orbital longitude, since the time for the Alfv\’en waves to reach the Jovian ionosphere varies accordingly. Using spectral images of the Main Alfv\’en Wing auroral spots collected by Juno-UVS during the first forty-three orbits, this work provides the first empirical model of the Io, Europa and Ganymede equatorial lead angles for the northern and southern hemispheres. Alfv\’en travel times between the three innermost Galilean moons to Jupiter’s northern and southern hemispheres are estimated from the lead angle measurements. We also demonstrate the accuracy of the mapping from the Juno magnetic field reference model (JRM33) at the completion of the prime mission for M-shells extending to at least 15RJ . Finally, we shows how the added knowledge of the lead angle can improve the interpretation of the moon-induced decametric emissions.

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V. Hue, R. Gladstone, C. Louis, et. al.
Mon, 1 May 23
13/51

Comments: 20 pages, 8 figures, Accepted for publication in Journal of Geophysical Research: Space Physics on 20 April 2023

Limitations in Testing the Lense-Thirring Effect with LAGEOS and the Newly Launched Geodetic Satellite LARES 2 [CL]

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http://arxiv.org/abs/2304.14649


The new geodetic satellite LARES 2, cousin of LAGEOS and sharing with it almost the same orbital parameters apart from the inclination, displaced by 180 deg, was launched last year. Its proponents suggest using the sum of the nodes of LAGEOS and of LARES 2 to measure the sum of the Lense-Thirring node precessions independently of the systematic bias caused by the even zonal harmonics of the geopotential, claiming a final $\simeq 0.2$ percent total accuracy. In fact, the actual orbital configurations of the two satellites do not allow one to attain the sought for mutual cancellation of their classical node precessions due to the Earth’s quadrupole mass moment, as their sum is still $\simeq 5000$ times larger than the added general relativistic rates. This has important consequences. One is that the current uncertainties in the eccentricities and the inclinations of both satellites do not presently allow the stated accuracy goal to be met, needing improvements of 3-4 orders of magnitude. Furthermore, the imperfect knowledge of the Earth’s angular momentum $S$ impacts the uncancelled sum of the node precessions, from 150 to 4900 percent of the relativistic signal depending on the uncertainty assumed in $S$. It is finally remarked that the real breakthrough in reliably testing the gravitomagnetic field of the Earth would consist in modeling it and simultaneously estimating one or more dedicated parameter(s) along with other ones characterising the geopotential, as is customarily performed for any other dynamical feature.

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L. Iorio
Mon, 1 May 23
15/51

Comments: LaTex2e, 17 pages, no figures, no tables

Cyclic Variability in Brightness of the Young Solar Analog BE Ceti [SSA]

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http://arxiv.org/abs/2304.14794


BE Cet is a young solar analog with an age of 0.6 Gyr and a rotation period of 7.655 days. According to chromospheric and photospheric indices, its activity is higher than the solar one. An analysis of photometric data on the time interval between 1977 and 2019 shows the presence of only 6.76 yr cyclic variations in the mean brightness with an amplitude of 0.02 mag. The obtained cycle is 1-2 yr shorter in comparison with the chromospheric cycle determined earlier, whose length was estimated to be 9 or 7.6 yr. Parameters of the cycle, its amplitude and duration change slightly in different epochs. The short-term light variations due to rotational modulation occur with an increase in amplitude up to 0.05 mag near the activity cycle minimum and a decrease in its maximum. Some events of a rapid increase in brightness of 0.2-0.6 mag may be considered as flares.

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N. Bondar’ and M. Katsova
Mon, 1 May 23
20/51

Comments: 6 pages, 3 figures, 1 table

Systematics of planetary ephemeris reference frames inferred from pulsar timing astrometry [EPA]

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http://arxiv.org/abs/2304.14677


This study aims to investigate the systematics in planetary ephemeris reference frames through pulsar timing observations. We used the published data sets from several pulsar timing arrays and performed timing analyses for each pulsar using different planetary ephemerides retrieved from the Jet Propulsion Laboratory’s Development Ephemeris (DE), Ephemeris of Planets and the Moon (EPM), and INPOP (Int\’egration Num\’erique Plan\’etaire de l’Observatoire de Paris). Then, we compared the timing solutions and modeled the differences in position and proper motion by vector spherical harmonics of the first degree. The timing solutions were also compared with those determined by very long baseline interferometry (VLBI) astrometry. The orientation offsets between the latest editions of the DE, EPM, and INPOP series do not exceed 0.4 milliarcseconds (mas), while the relative spins between these ephemerides are less than 5 microarcseconds per year ($\mathrm{\mu as\,yr^{-1}}$). We do not detect significant glides in either position or proper motion between these ephemerides. The orientation of the pulsar timing frames deviates from that of the VLBI frame from zero by approximately $\mathrm{0.4\,mas}$ when considering the formal uncertainty and possible systematics. The orientation of current planetary ephemeris frames is as accurate as at least 0.4 mas, and the nonrotating is better than $\mathrm{5\,\mu as\,yr^{-1}}$.

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N. Liu, Z. Zhu, J. Antoniadis, et. al.
Mon, 1 May 23
22/51

Comments: 17 pages, 14 figures, 6 tables, to be accepted for publication at A&A

A von Mises-Fisher Distribution for the Orbital Poles of the Plutinos [EPA]

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http://arxiv.org/abs/2304.14478


Small solar system bodies have widely dispersed orbital poles, posing challenges to dynamical models of solar system origin and evolution. To characterize the orbit pole distribution of dynamical groups of small bodies it helps to have a functional form for a model of the distribution function. Previous studies have used the small-inclination approximation and adopted variations of the normal distribution to model orbital inclination dispersions. Because the orbital pole is a directional variable, its distribution can be more appropriately modeled with directional statistics. We describe the von Mises-Fisher (vMF) distribution on the surface of the unit sphere for application to small bodies’ orbital poles. We apply it to the orbit pole distribution of the observed Plutinos. We find a mean pole located at inclination of 3.57 degrees and a longitude of ascending node of 124.38 degrees (in the J2000 reference frame), with a 99.7 per cent confidence cone of half-angle 1.68 degrees. We also estimate a debiased mean pole located 4.6 degrees away, at an inclination of 2.26 degrees and a longitude of ascending node of 292.69 degrees, of similar-size confidence cone. The vMF concentration parameter of Plutino inclinations (relative to either mean pole estimate) is 31.6. This resembles a Rayleigh distribution function with a width parameter of 10.2 degrees. Unlike previous models, the vMF model naturally accommodates all physical inclinations (and no others), whereas Rayleigh or Gaussian models must be truncated to the physical inclination range 0-180 degrees. Further work is needed to produce a theory for the mean pole of the Plutinos against which to compare the observational results.

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I. Matheson, R. Malhotra and J. Keane
Mon, 1 May 23
25/51

Comments: 10 pages, 7 figures. Accepted for Monthly Notices of the Royal Astronomical Society (MNRAS) in April 2023

The mass determination of TOI-519 b: a close-in giant planet transiting a metal-rich mid-M dwarf [EPA]

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http://arxiv.org/abs/2304.14703


We report the mass determination of TOI-519 b, a transiting substellar object around a mid-M dwarf. We carried out radial velocity measurements using Subaru / InfraRed Doppler (IRD), revealing that TOI-519 b is a planet with a mass of $0.463^{+0.082}{-0.088}~M{\rm Jup}$. We also find that the host star is metal rich ($\rm [Fe/H] = 0.27 \pm 0.09$ dex) and has the lowest effective temperature ($T_{\rm eff}=3322 \pm 49$ K) among all stars hosting known close-in giant planets based on the IRD spectra and mid-resolution infrared spectra obtained with NASA Infrared Telescope Facility / SpeX. The core mass of TOI-519 b inferred from a thermal evolution model ranges from $0$ to $\sim30~M_\oplus$, which can be explained by both the core accretion and disk instability models as the formation origins of this planet. However, TOI-519 is in line with the emerging trend that M dwarfs with close-in giant planets tend to have high metallicity, which may indicate that they formed in the core accretion model. The system is also consistent with the potential trend that close-in giant planets around M dwarfs tend to be less massive than those around FGK dwarfs.

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T. Kagetani, N. Narita, T. Kimura, et. al.
Mon, 1 May 23
33/51

Comments: 10 pages, 5 figures. Accepted for publication in PASJ

Observations of planet forming disks in multiple stellar systems [SSA]

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http://arxiv.org/abs/2304.14450


The demographic of circumstellar disks, the birthplaces of planets, is diverse and rich in disks featuring rings, gaps, spirals, filaments, and arcs. Many studies revealing these disk structures have focused on objects around single stars and disks in isolation. The scenario is more complex if binarity or multiplicity is involved; most stars are part of multiple systems in crowded star-forming regions. How does the presence of one or more stellar companions affect the shape and size of the circumstellar disks? Here we review the landscape of results from optical, infrared, and (sub-) millimeter observations of the effects of multiplicity on protoplanetary disks, emphasizing the demographic studies of nearby molecular clouds and the high-resolution studies of multiple disk systems.

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A. Zurlo, R. Gratton, S. Pérez, et. al.
Mon, 1 May 23
39/51

Comments: Invited review accepted in EPJ+

Gas distribution in ODISEA sources from ALMA long-baseline observations in $^{12}$CO(2-1) [EPA]

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http://arxiv.org/abs/2304.15002


The $^{12}$CO rotational lines in protoplanetary discs are good tracers of the total spatial extension of the gas component, and potentially planet-disc interactions. We present ALMA long baseline observations of the $^{12}$CO(2-1) line of ten protoplanetary discs from the Ophiuchus DIsc Survey Employing ALMA (ODISEA) project, aiming to set constraints on the gas distribution of these sources. The position angle of the gaseous disc can be inferred for five sources using high-velocity channels, which trace the gas in the inner part of the disc. We compare the high-velocity PAs to the orientations inferred from the continuum, representative of the orientation over $\sim$ 53 to 256 au in these resolved discs. We find a significant difference in orientation for DoAr 44, which is evidence of a tilted inner disc. Eight discs show evidence of gas inside inner dust cavities or gaps, and the disc of ISO-Oph 196 is not detected in $^{12}$CO(2-1), except for the compact signal located inside its dust cavity. Our observations also point out a possible outflow in WLY 2-63.

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J. Antilen, S. Casassus, L. Cieza, et. al.
Mon, 1 May 23
45/51

Comments: N/A

Mind the Gap I: H$α$ Activity of M Dwarfs Near the Partially/Fully Convective Boundary and a New H$α$ Emission Deficiency Zone on the Main Sequence [SSA]

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http://arxiv.org/abs/2304.14452


Since identifying the gap in the H-R Diagram (HRD) marking the transition between partially and fully convective interiors, a unique type of slowly pulsating M dwarf has been proposed. These unstable M dwarfs provide new laboratories in which to understand how changing interior structures result in potentially observable activity at the surface. In this work, we report the results of the largest high-resolution spectroscopic H$\alpha$ emission survey to date spanning this transition region, including 480 M dwarfs observed using the CHIRON spectrograph at CTIO/SMARTS 1.5-m. We find that M dwarfs with H$\alpha$ in emission are almost entirely found 0 to 0.5 magnitude above the top edge of the gap in the HRD, whereas effectively no stars in and below the gap show emission. Thus, the top edge of the gap marks a relatively sharp activity transition and there is no anomalous H$\alpha$ activity for stars in the gap. We also identify a new region at 10.3 $<M_{G}<$ 10.8 on the main sequence where fewer M dwarfs exhibit H$\alpha$ emission compared to M dwarfs above and below this magnitude range. Careful evaluation of literature results indicates that 1) rotation and H$\alpha$ activity distributions on the main sequence are closely related, and 2) fewer stars in this absolute magnitude range rotate in less than $\sim$13 days than populations surrounding this region. This result suggests that the most massive fully convective stars lose their angular momentum faster than both partially convective stars and less massive fully convective stars.

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W. Jao, T. Henry, R. White, et. al.
Mon, 1 May 23
51/51

Comments: 30 pages, 18 figures, and 6 table. Submitted to AJ

Combined analysis of stellar and planetary absorption lines via global forward-transit simulations [EPA]

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http://arxiv.org/abs/2304.13759


We characterise the planet-occulted line distortions (POLDs) in absorption spectra of transiting planets, that arise from proxies used for the occulted stellar lines and investigate the impact of stellar rotation, centre-to-limb variations, and broadband limb-darkening. We used the EVaporating Exoplanets (EVE) code to generate realistic stellar spectra during the transit of exoplanets, accounting for the 3D geometry of the system’s architecture and atmospheric transit, as well as for spectral variations over the stellar disc. The absorption spectra were calculated using approaches drawn from the literature and compared to the expected signal. The POLDs from stellar rotation are dominant for moderate to fast rotating stars, reaching amplitudes comparable to atmospheric signals, but they can be mitigated by shifting the stellar line proxies to the radial velocity of the planet-occulted region. Centre-to-limb variations become dominant for slow rotators and are more easily mitigated at the stellar limb. We re-interpret the ESPRESSO data of two iconic systems and confirm that the sodium signature from HD209458b mainly arises from POLDs. However, we unveil a possible contribution from the planetary atmosphere that warrants further observations. For MASCARA-1b, we did not find evidence for atmospheric sodium absorption and we can fully explain the observed signature by a POLD for super-solar stellar sodium abundance. We studied POLDs dependency on star and planet properties, and on the proxy used for planet-occulted lines. Distinguishing planetary absorption signatures from POLDs is challenging without access to accurate estimates of the local stellar spectrum and system orbital parameters. We propose a way to mitigate POLDs and improve atmospheric characterisation, by using simultaneous forward modelling of both the star and the planet to simulate the global observed signatures.

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W. Dethier and V. Bourrier
Fri, 28 Apr 23
6/68

Comments: N/A

Mineralogical Characterization and Phase Angle Study of Two Binary Near-Earth Asteroids, Potential Targets for NASA's Janus Mission [EPA]

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http://arxiv.org/abs/2304.13781


Ground-based characterization of spacecraft targets prior to mission operations is critical to properly plan and execute measurements. Understanding surface properties, like mineralogical composition and phase curves (expected brightness at different viewing geometries) informs data acquisition during the flybys. Binary near-Earth asteroids (NEA) (35107) 1991 VH and (175706) 1996 FG3 were selected as potential targets of the National Aeronautics and Space Administration’s (NASA) dual spacecraft Janus mission. We observed 1991 VH using the 3-m NASA Infrared Telescope Facility (IRTF) on Mauna Kea, Hawaii, on July 26, 2008. 1996 FG3 was observed with the IRTF for seven nights during the spring of 2022. Compositional analysis of 1991 VH revealed that this NEA is classified as an Sq-type in the Bus-DeMeo taxonomy classification, with a composition consistent with LL ordinary chondrites. Using thermal modeling, we computed the thermally corrected spectra for 1996 FG3 and the corresponding best fit albedo of about 2-3% for the best spectra averaged for each night. Our spectral analysis indicates that this NEA is a Ch-type. The best possible meteorite analogs for 1996 FG3, based on curve matching, are two carbonaceous chondrites, Y-86789 and Murchison. No rotational variation was detected in the spectra of 1996 FG3, which means there may not be any heterogeneities on the surface of the primary. However, a clear phase reddening effect was observed in our data, confirming findings from previous ground-based studies.

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L. Corre, J. Sanchez, V. Reddy, et. al.
Fri, 28 Apr 23
16/68

Comments: 18 pages, 8 figures, 1 table, accepted for publication in the Planetary Science Journal

Simulation of the Earth's radio leakage from mobile towers as seen from selected nearby stellar systems [EPA]

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http://arxiv.org/abs/2304.13779


Mobile communication towers represent a relatively new but growing contributor to the total radio leakage associated with planet Earth. We investigate the overall power contribution of mobile communication towers to the Earth\’s radio leakage budget, as seen from a selection of different nearby stellar systems. We created a model of this leakage using publicly available data of mobile tower locations. The model grids the planet’s surface into small, computationally manageable regions, assuming a simple integrated transmission pattern for the mobile antennas. In this model, these mobile tower regions rise and set as the Earth rotates. In this way, a dynamic power spectrum of the Earth was determined, summed over all cellular frequency bands. We calculated this dynamic power spectrum from three different viewing points, HD 95735, Barnard star, and Alpha Centauri A. Our preliminary results demonstrate that the peak power leaking into space from mobile towers is $\sim 4$GW. This is associated with LTE mobile tower technology emanating from the East Coast of China as viewed from HD 95735. We demonstrate that the mobile tower leakage is periodic, direction dependent, and could not currently be detected by a nearby civilization located within 10 light years of the Earth, using instrumentation with a sensitivity similar to the Green Bank Telescope. We plan to extend our model to include more powerful 5G mobile systems, radar installations, ground based uplinks (including the Deep Space Network), and various types of satellite services, including low Earth orbit constellations such as Starlink and OneWeb.

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R. Saide, M. Garrett and N. Heeralall-Issur
Fri, 28 Apr 23
17/68

Comments: N/A

Tidal Forcing on the Sun and the 11-year Solar Activity Cycle [SSA]

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http://arxiv.org/abs/2304.14168


The hypothesis that tidal forces on the Sun are related to the modulations of the solar-activity cycle has gained increasing attention. The works proposing physical mechanisms of planetary action via tidal forcing have in common that quasi-alignments between Venus, Earth, and Jupiter (V-E-J configurations) would provide a basic periodicity of $\approx 11.0$ years able to synchronize the operation of solar dynamo with these planetary configurations. Nevertheless, the evidence behind this particular tidal forcing is still controversial. In this context we develop, for the first time, the complete Sun’s tide-generating potential (STGP) in terms of a harmonic series, where the effects of different planets on the STGP are clearly separated and identified. We use a modification of the spectral analysis method devised by Kudryavtsev (J. Geodesy. 77, 829, 2004; Astron. Astrophys. 471, 1069, 2007b) that permits to expand any function of planetary coordinates to a harmonic series over long time intervals. We build a catalog of 713 harmonic terms able to represent the STGP with a high degree of precision. We look for tidal forcings related to V-E-J configurations and specifically the existence of periodicities around $11.0$ years.
Although the obtained tidal periods range from $\approx$ 1000 years to 1 week, we do not find any $\approx$ 11.0 years period. The V-E-J configurations do not produce any significant tidal term at this or other periods. The Venus tidal interaction is absent in the 11-year spectral band, which is dominated by Jupiter’s orbital motion. The planet that contributes the most to the STGP in three planets configurations, along with Venus and Earth, is Saturn. An $\approx 11.0$ years tidal period with a direct physical relevance on the 11-year-like solar-activity cycle is highly improbable.

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R. Cionco, S. Kudryavtsev and W. Soon
Fri, 28 Apr 23
23/68

Comments: Accepted (April 2023) to be published in Solar Physics

High-contrast detection of exoplanets with a kernel-nuller at the VLTI [IMA]

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http://arxiv.org/abs/2304.14193


Context: The conventional approach to direct imaging has been the use of a single aperture coronagraph with wavefront correction via extreme adaptive optics. Such systems are limited to observing beyond an inner working (IWA) of a few {\lambda}/D. Nulling interferometry with two or more apertures will enable detections of companions at separations at and beyond the formal diffraction limit.
Aims: This paper evaluates the astrophysical potential of a kernel-nuller as the prime high-contrast imaging mode of the Very Large Telescope Interferometer (VLTI).
Methods: By taking into account baseline projection effects which are induced by Earth rotation, we introduce some diversity in the response of the nuller as a function of time. This response is depicted by transmission maps. We also determine whether we can extract the astrometric parameters of a companion from the kernel outputs, which are the primary intended observable quantities of the kernel-nuller. This then leads us to comment on the characteristics of a possible observing program for the discovery of exoplanets.
Results: We present transmission maps for both the raw nuller outputs and their subsequent kernel outputs. To further examine the properties of the kernel-nuller, we introduce maps of the absolute value of the kernel output. We also identify 38 targets for the direct detection of exoplanets with a kernel-nuller at the focus of the VLTI.
Conclusions: With continued upgrades of the VLTI infrastructure that will reduce fringe tracking residuals, a kernel-nuller would enable the detection of young giant exoplanets at separations < 10 AU, where radial velocity and transit methods are more sensitive.

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P. Chingaipe, F. Martinache, N. Cvetojevic, et. al.
Fri, 28 Apr 23
33/68

Comments: 13 pages, 12 figures

Distinguishing a planetary transit from false positives: a Transformer-based classification for planetary transit signals [EPA]

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http://arxiv.org/abs/2304.14283


Current space-based missions, such as the Transiting Exoplanet Survey Satellite (TESS), provide a large database of light curves that must be analysed efficiently and systematically. In recent years, deep learning (DL) methods, particularly convolutional neural networks (CNN), have been used to classify transit signals of candidate exoplanets automatically. However, CNNs have some drawbacks; for example, they require many layers to capture dependencies on sequential data, such as light curves, making the network so large that it eventually becomes impractical. The self-attention mechanism is a DL technique that attempts to mimic the action of selectively focusing on some relevant things while ignoring others. Models, such as the Transformer architecture, were recently proposed for sequential data with successful results. Based on these successful models, we present a new architecture for the automatic classification of transit signals. Our proposed architecture is designed to capture the most significant features of a transit signal and stellar parameters through the self-attention mechanism. In addition to model prediction, we take advantage of attention map inspection, obtaining a more interpretable DL approach. Thus, we can identify the relevance of each element to differentiate a transit signal from false positives, simplifying the manual examination of candidates. We show that our architecture achieves competitive results concerning the CNNs applied for recognizing exoplanetary transit signals in data from the TESS telescope. Based on these results, we demonstrate that applying this state-of-the-art DL model to light curves can be a powerful technique for transit signal detection while offering a level of interpretability.

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H. Salinas, K. Pichara, R. Brahm, et. al.
Fri, 28 Apr 23
34/68

Comments: N/A

Thermal Tomography of the Inner Regions of Protoplanetary Disks with the ngVLA and ALMA [EPA]

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http://arxiv.org/abs/2304.14192


Understanding the temperature structure of protoplanetary disks is crucial for answering the fundamental question of when and where in the disks rocky planets like our own form. However, the thermal structure of the inner few au of the disks is poorly understood not only because of lack of observational constraints but also because of the uncertainty of accretion heating processes. Here, we propose thermal tomography of the inner regions of protoplanetary disks with the ngVLA and ALMA. The proposed approach is based on the assumption that the inner disk regions are optically thick at submillimeter wavelengths but are marginally optically thin at longer millimeter wavelengths. By combining high-resolution millimeter continuum images from the ngVLA with submillimeter images at comparable resolutions from ALMA, we will be able to reconstruct the radial and vertical structure of the inner few au disk regions. We demonstrate that the thermal tomography we propose can be used to constrain the efficiency of midplane accretion heating, a process that controls the timing of snow-line migration to the rocky planet-forming region, in the few au regions of protoplanetary disks at a distance of 140 pc.

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S. Okuzumi, M. Momose and A. Kataoka
Fri, 28 Apr 23
36/68

Comments: 4 pages, 3 figures, ngVLA-Japan Memo Series P006 (2021), this https URL

A Measurement of the Kuiper Belt's Mean Plane From Objects Classified By Machine Learning [EPA]

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http://arxiv.org/abs/2304.14312


Mean plane measurements of the Kuiper Belt from observational data are of interest for their potential to test dynamical models of the solar system. Recent measurements have yielded inconsistent results. Here we report a measurement of the Kuiper Belt’s mean plane with a sample size more than twice as large as in previous measurements. The sample of interest is the non-resonant Kuiper belt objects, which we identify by using machine learning on the observed Kuiper Belt population whose orbits are well-determined. We estimate the measurement error with a Monte Carlo procedure. We find that the overall mean plane of the non-resonant Kuiper Belt (semimajor axis range 35-150 au) and also that of the classical Kuiper Belt (semimajor axis range 42-48 au) are both close to (within about 0.7 degrees) but distinguishable from the invariable plane of the solar system to greater than 99.7% confidence. When binning the sample into smaller semimajor axis bins, we find the measured mean plane mostly consistent with both the invariable plane and the theoretically expected Laplace surface forced by the known planets. Statistically significant discrepancies are found only in the semimajor axis ranges 40.3-42 au and 45-50 au; these ranges are in proximity to a secular resonance and Neptune’s 2:1 mean motion resonance where the theory for the Laplace surface is likely to be inaccurate. These results do not support a previously reported anomalous warp at semimajor axes above 50 au.

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I. Matheson and R. Malhotra
Fri, 28 Apr 23
38/68

Comments: 15 pages, 4 figures. Accepted for The Astronomical Journal

Debris Rings from Extrasolar Irregular Satellites [EPA]

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http://arxiv.org/abs/2304.13753


Irregular satellites are the minor bodies found orbiting all four Solar System giant planets, with large semi-major axes, eccentricities, and inclinations. Previous studies have determined that the Solar System’s irregular satellites are extremely collisionally evolved populations today, having lost $\sim$99 per cent of their initial mass over the course of hundreds of Myr. Such an evolution implies that the irregular satellites must have produced a population of dusty collisional debris in the past, which is potentially observable due to the resulting reprocessing of stellar light. In this paper we examine the signatures of the debris discs produced by extrasolar analogues of this process. Radiation pressure, quantified by the parameter $\beta$, is the driving force behind the liberation of dust grains from the planetary Hill sphere, and results in the formation of circumstellar dust rings, even in the absence of an underlying belt of asteroids in the system. Our simulated discs reproduce many of the same features seen in some classes of observed debris discs, such as thin ring morphology, a large blowout size, and azimuthal symmetry. We compare our simulated discs’ radial profiles to those of the narrow dust rings observed around Fomalhaut and HR 4796A, and show that they can broadly reproduce the observed radial distribution of dust.

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K. Hayakawa and B. Hansen
Fri, 28 Apr 23
44/68

Comments: 19 pages, 17 figures

Molecular Outgassing in Centaur 29P/Schwassmann-Wachmann 1 During Its Exceptional 2021 Outburst: Coordinated Multi-Wavelength Observations Using nFLASH at APEX and iSHELL at the NASA-IRTF [EPA]

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http://arxiv.org/abs/2304.14324


The extraordinary 2021 September-October outburst of Centaur 29P/Schwassmann-Wachmann 1 afforded an opportunity to test the composition of primitive Kuiper disk material at high sensitivity. We conducted nearly simultaneous multi-wavelength spectroscopic observations of 29P/Schwassmann-Wachmann 1 using iSHELL at the NASA Infrared Telescope Facility and nFLASH at the Atacama Pathfinder EXperiment (APEX) on 2021 October 6, with follow-up APEX/nFLASH observations on 2021 October 7 and 2022 April 3. This coordinated campaign between near-infrared and radio wavelengths enabled us to sample molecular emission from a wealth of coma molecules and to perform measurements that cannot be accomplished with either wavelength alone. We securely detected CO emission on all dates with both facilities, including velocity-resolved spectra of the CO (J=2-1) transition with APEX/nFLASH and multiple CO (v=1-0) rovibrational transitions with IRTF/iSHELL. We report rotational temperatures, coma kinematics, and production rates for CO and stringent (3-sigma) upper limits on abundance ratios relative to CO for CH4, C2H6, CH3OH, H2CO, CS, and OCS. Our upper limits for CS/CO and OCS/CO represent their first values in the literature for this Centaur. Upper limits for CH4, C2H6, CH3OH, and H2CO are the most stringent reported to date, and are most similar to values found in ultra CO-rich Oort cloud comet C/2016 R2 (PanSTARRS), which may have implications for how ices are preserved in cometary nuclei. We demonstrate the superb synergy of coordinated radio and near-infrared measurements, and advocate for future small body studies that jointly leverage the capabilities of each wavelength.

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N. Roth, S. Milam, M. DiSanti, et. al.
Fri, 28 Apr 23
46/68

Comments: N/A

Orbital pathways for a Lunar-Ejecta Origin of the Near-Earth Asteroid Kamo`oalewa [EPA]

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http://arxiv.org/abs/2304.14136


The near-Earth asteroid, Kamooalewa (469219), is one of a small number of known quasi-satellites of Earth. Numerical simulations show that it transitions between quasi-satellite and horseshoe orbital states on centennial timescales, maintaining this dynamics over megayears. Its reflectance spectrum suggest a similarity to lunar silicates. Considering its Earth-like orbit and its physical resemblance to lunar surface materials, we explore the hypothesis that it might have originated as a debris-fragment from a meteoroidal impact with the lunar surface. We carry out numerical simulations of the dynamical evolution of particles launched from different locations on the lunar surface with a range of ejection velocities. As these ejecta escape the Earth-Moon environment and evolve into heliocentric orbits, we find that a small fraction of launch conditions yield outcomes that are compatible with Kamooalewa’s dynamical behavior. The most favored conditions are launch velocities slightly above the escape velocity from the trailing lunar hemisphere.

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J. Castro-Cisneros, R. Malhotra and A. Rosengren
Fri, 28 Apr 23
52/68

Comments: N/A

Removing Aliases in Time-Series Photometry [EPA]

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http://arxiv.org/abs/2304.13843


Ground-based, all-sky astronomical surveys are imposed with an inevitable day-night cadence that can introduce aliases in period-finding methods. We examined four different methods — three from the literature and a new one that we developed — that remove aliases to improve the accuracy of period-finding algorithms. We investigate the effectiveness of these methods in decreasing the fraction of aliased period solutions by applying them to the Zwicky Transient Facility (ZTF) and the LSST Solar System Products Data Base (SSPDB) asteroid datasets. We find that the VanderPlas method had the worst accuracy for each survey. The mask and our newly proposed window method yields the highest accuracy when averaged across both datasets. However, the Monte Carlo method had the highest accuracy for the ZTF dataset, while for SSPDB, it had lower accuracy than the baseline where none of these methods are applied. Where possible, detailed de-aliasing studies should be carried out for every survey with a unique cadence.

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D. Kramer, M. Gowanlock, D. Trilling, et. al.
Fri, 28 Apr 23
67/68

Comments: N/A

Applying a temporal systematics model to vector Apodizing Phase Plate coronagraphic data: TRAP4vAPP [IMA]

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http://arxiv.org/abs/2304.14063


The vector Apodizing Phase Plate (vAPP) is a pupil plane coronagraph that suppresses starlight by forming a dark hole in its point spread function (PSF). The unconventional and non-axisymmetrical PSF arising from the phase modification applied by this coronagraph presents a special challenge to post-processing techniques. We aim to implement a recently developed post-processing algorithm, temporal reference analysis of planets (TRAP) on vAPP coronagraphic data. The property of TRAP that uses non-local training pixels, combined with the unconventional PSF of vAPP, allows for more flexibility than previous spatial algorithms in selecting reference pixels to model systematic noise. Datasets from two types of vAPPs are analysed: a double grating-vAPP (dgvAPP360) that produces a single symmetric PSF and a grating-vAPP (gvAPP180) that produces two D-shaped PSFs. We explore how to choose reference pixels to build temporal systematic noise models in TRAP for them. We then compare the performance of TRAP with previously implemented algorithms that produced the best signal-to-noise ratio (S/N) in companion detections in these datasets. We find that the systematic noise between the two D-shaped PSFs is not as temporally associated as expected. Conversely, there is still a significant number of systematic noise sources that are shared by the dark hole and the bright side in the same PSF. We should choose reference pixels from the same PSF when reducing the dgvAPP360 dataset or the gvAPP180 dataset with TRAP. In these datasets, TRAP achieves results consistent with previous best detections, with an improved S/N for the gvAPP180 dataset.

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P. Liu, A. Bohn, D. Doelman, et. al.
Fri, 28 Apr 23
68/68

Comments: 15 pages, 10 figures, accepted to A&A

The invasion of a free floating planet and the number asymmetry of Jupiter Trojans [EPA]

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http://arxiv.org/abs/2304.13598


This paper extends our previous study (Li et al. 2023) of the early evolution of Jupiter and its two Trojan swarms by introducing the possible perturbations of a free floating planet (FFP) invading the Solar System. In the framework of the invasion of a FFP, we aim to provide some new scenarios to explain the number asymmetry of the L4 and L5 Jupiter Trojans, and some other observed features. We investigate two different cases: (i) The indirect case, where Jupiter experiences a scattering encounter with the FFP and jumps outwards at a speed that is much higher than that considered in(Li et al. 2023), resulting in a change in the numbers of the L4 (N4) and L5 (N5) Trojans swarms. (ii) The direct case, in which the FFP traverses the L5 region and affects the stability of the local Trojans. In the indirect case, the outward migration of Jupiter can be fast enough to make the L4 islands disappear temporarily, inducing a resonant amplitude increase of the local Trojans. After the migration is over, the L4 Trojans come back to the re-appeared and enlarged islands. As for the L5 islands, they always exist but expand even more considerably. Since the L4 swarm suffers less excitation in the resonant amplitude than the L5 swarm, more L4 Trojans are stable and could survive to the end. In the direct case, the FFP could deplete a considerable fraction of the L5 Trojans, while the L4 Trojans at large distances are not affected and all of them could survive. Both the indirect and direct cases could result in a number ratio of R45=N4/N5~1.6 that can potentially explain the current observations. The latter has the advantage of producing the observed resonant amplitude distribution. For achieving these results, we propose that the FFP should have a mass of at least of a few tens of Earth masses and its orbital inclination is allowed to be as high as 40 degrees.

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J. Li, Z. Xia, N. Georgakarakos, et. al.
Thu, 27 Apr 23
17/78

Comments: Accepted for publication in A&A, 13 pages, 7 figures, 5 tables

Gaussian processes for radial velocity modeling Better rotation periods and planetary parameters with the quasi-periodic kernel and constrained priors [EPA]

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http://arxiv.org/abs/2304.13381


In this study we present an analysis of the performance and properties of the quasi-periodic (QP) GP kernel, which is the multiplication of the squared-exponential kernel by the exponential-sine-squared kernel, based on an extensive set of synthetic RVs, into which the signature of activity was injected. We find that while the QP-GP rotation parameter matches the simulated rotation period of the star, the length scale cannot be directly connected to the spot lifetimes on the stellar surface. Regarding the setup of the priors for the QP-GP, we find that it can be advantageous to constrain the QP-GP hyperparameters in different ways depending on the application and the goal of the analysis. We find that a constraint on the length scale of the QP-GP can lead to a significant improvement in identifying the correct rotation period of the star, while a constraint on the rotation hyperparameter tends to lead to improved planet detection efficiency and more accurately derived planet parameters. Even though for most of the simulations the Bayesian evidence performed as expected, we identified not far-fetched cases where a blind adoption of this metric would lead to wrong conclusions. We conclude that modeling stellar astrophysical noise by using a QP-GP considerably improves detection efficiencies and leads to precise planet parameters. Nevertheless, there are also cases in which the QP-GP does not perform optimally, for example RV variations dynamically evolving on short timescales or a mixture of a very stable activity component and random variations. Knowledge of these limitations is essential for drawing correct conclusions from observational data.

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S. Stock, J. Kemmer, D. Kossakowski, et. al.
Thu, 27 Apr 23
35/78

Comments: Accepted for publication in A&A, Abstract shortened to fit the arXiv requirements

Simulations of Protoplanetary Disk Dispersal: Stellar Mass Dependence of the Disk Lifetime [SSA]

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http://arxiv.org/abs/2304.13316


Recent infrared and submillimeter observations suggest that the protoplanetary disk lifetime depends on the central stellar mass. The disk dispersal is thought to be driven by viscous accretion, magneto-hydrodynamics (MHD) winds, and photoevaporation by the central star. We perform a set of one-dimensional simulations of long-term disk evolution that include all the three processes. We vary the stellar mass in the range of 0.5-7M${\odot}$, and study the mass dependence of the disk evolution. We show that a significant fraction of the disk gas is lost by MHD winds in the early stage, but the later disk evolution is mainly governed by photoevaporation. The disk radius decreases as photoevaporation clears out the gas in the outer disk efficiently. The qualitative evolutionary trends of the disk mass are remarkably similar for the wide range of the central stellar mass we consider, and the time evolution of the disk mass can be well fitted by a simple function. The dispersal time is approximately ten million years for low mass stars with weak mass dependence, but gets as short as two million years around a 7M${\odot}$ star. In the latter case, a prominent inner hole is formed by the combined effect of accretion and MHD winds within about one million years. The strength of the MHD wind and viscous accretion controls the overall mass-loss rate, but does not alter the dependence of the dispersal timescale on the central stellar mass.

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A. Komaki, S. Fukuhara, T. Suzuki, et. al.
Thu, 27 Apr 23
38/78

Comments: 14 pages, 10 figures, 1 table

Reliable and Repeatable Transit Through Cislunar Space Using the 2:1 Resonant Spatial Orbit Family [EPA]

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http://arxiv.org/abs/2304.13584


This work focuses on the identification of reliable and repeatable spatial (three-dimensional) trajectories that link the Earth and the Moon. For this purpose, this paper aims to extend the 2:1 resonant prograde family and 2:1 resonant retrograde family to three dimensions and to introduce spatial orbits that are not currently present in the literature. These orbits, named the 2:1 resonant spatial family, bifurcate from the two-dimensional families and smoothly transition between them in phase space. The stability properties of this new family of resonant orbits are discussed, and, interestingly, this family includes marginally stable members. Furthermore, this new family of orbits is applied to several engineering problems in the Earth-Moon system. First, this paper selects an appropriate member of 2:1 resonant spatial family on the basis of its stability properties and relationships with other multibody orbits in the regime. Next, this work combines this trajectory with momentum exchange tethers to transit payloads throughout the system in a reliable and repeatable fashion. Finally, this paper studies the process of aborting a catch and related recovery opportunities.

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A. Binder and D. Arnas
Thu, 27 Apr 23
42/78

Comments: 33 pages, 31 figures

Narrow loophole for H2-dominated atmospheres on habitable rocky planets around M dwarfs [EPA]

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http://arxiv.org/abs/2304.13659


Habitable rocky planets around M dwarfs that have H2-dominated atmospheres, if they exist, would permit characterizing habitable exoplanets with detailed spectroscopy using JWST, owing to their extended atmospheres and small stars. However, the H2-dominated atmospheres that are consistent with habitable conditions cannot be too massive, and a moderate-size H2-dominated atmosphere will lose mass to irradiation-driven atmospheric escape on rocky planets around M dwarfs. We evaluate volcanic outgassing and serpentinization as two potential ways to supply H2 and form a steady-state H2-dominated atmosphere. For rocky planets of 1-7 Earth mass and early, mid, and late M dwarfs, the expected volcanic outgassing rates from a reduced mantle fall short of the escape rates by >~1 order of magnitude, and a generous upper limit of the serpentinization rate is still less than the escape rate by a factor of a few. Special mechanisms that may sustain the steady-state H2-dominated atmosphere include direct interaction between liquid water and mantle, heat-pipe volcanism from a reduced mantle, and hydrodynamic escape slowed down by efficient upper-atmospheric cooling. It is thus unlikely to find moderate-size, H2-dominated atmospheres on rocky planets of M dwarfs that would support habitable environments.

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R. Hu, F. Gaillard and E. Kite
Thu, 27 Apr 23
47/78

Comments: Accepted for publication in ApJ Letters

FU Orionis disk outburst: evidence for a gravitational instability scenario triggered in a magnetically dead zone [SSA]

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http://arxiv.org/abs/2304.13414


Context: FUors outbursts are a crucial stage of accretion in young stars. However a complete mechanism at the origin of the outburst still remains missing. Aims: We aim at constraining the instability mechanism in FU Orionis star itself, by directly probing the size and the evolution in time of the outburst region with near-infrared interferometry, and to confront it to physical models of this region. Methods: FU Orionis has been a regular target of near-infrared interferometry. In this paper, we analyze more than 20 years of interferometric observations to perform a temporal monitoring of the region of the outburst, and compare it to the spatial structure deduced from 1D MHD simulations. Results: We measure from the interferometric observations that the size variation of the outburst region is compatible with a constant or slightly decreasing size over time in the H and K band. The temporal variation and the mean sizes are consistently reproduced by our 1D MHD simulations. We find that the most compatible scenario is a model of an outburst occurring in a magnetically layered disk, where a Magneto-Rotational Instability (MRI) is triggered by a Gravitational Instability (GI) at the outer edge of a dead-zone. The scenario of a pure Thermal Instability (TI) fails to reproduce our interferometric sizes since it can only be sustained in a very compact zone of the disk <0.1 AU. The scenario of MRI-GI could be compatible with an external perturbation enhancing the GI, such as tidal interactions with a stellar companion, or a planet at the outer edge of the dead-zone. Conclusions: The layered disk model driven by MRI turbulence is favored to interpret the spatial structure and temporal evolution of FU Orionis outburst region. Understanding this phase gives a crucial link between the early phase of disk evolution and the process of planet formation in the first inner AUs.

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G. Bourdarot, J. Berger, G. Lesur, et. al.
Thu, 27 Apr 23
51/78

Comments: Accepted for publication in A&A

Onboard Science Instrument Autonomy for the Detection of Microscopy Biosignatures on the Ocean Worlds Life Surveyor [IMA]

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http://arxiv.org/abs/2304.13189


The quest to find extraterrestrial life is a critical scientific endeavor with civilization-level implications. Icy moons in our solar system are promising targets for exploration because their liquid oceans make them potential habitats for microscopic life. However, the lack of a precise definition of life poses a fundamental challenge to formulating detection strategies. To increase the chances of unambiguous detection, a suite of complementary instruments must sample multiple independent biosignatures (e.g., composition, motility/behavior, and visible structure). Such an instrument suite could generate 10,000x more raw data than is possible to transmit from distant ocean worlds like Enceladus or Europa. To address this bandwidth limitation, Onboard Science Instrument Autonomy (OSIA) is an emerging discipline of flight systems capable of evaluating, summarizing, and prioritizing observational instrument data to maximize science return. We describe two OSIA implementations developed as part of the Ocean Worlds Life Surveyor (OWLS) prototype instrument suite at the Jet Propulsion Laboratory. The first identifies life-like motion in digital holographic microscopy videos, and the second identifies cellular structure and composition via innate and dye-induced fluorescence. Flight-like requirements and computational constraints were used to lower barriers to infusion, similar to those available on the Mars helicopter, “Ingenuity.” We evaluated the OSIA’s performance using simulated and laboratory data and conducted a live field test at the hypersaline Mono Lake planetary analog site. Our study demonstrates the potential of OSIA for enabling biosignature detection and provides insights and lessons learned for future mission concepts aimed at exploring the outer solar system.

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M. Wronkiewicz, J. Lee, L. Mandrake, et. al.
Thu, 27 Apr 23
69/78

Comments: 49 pages, 18 figures, submitted to The Planetary Science Journal on 2023-04-20

The interplay between pebble and planetesimal accretion in population synthesis models and its role in giant planet formation [EPA]

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http://arxiv.org/abs/2304.12788


In the core accretion scenario of planet formation, rocky cores grow by first accreting solids until they are massive enough to accrete gas. For giant planet formation this means that a massive core must form within the lifetime of the gas disk. The accretion of roughly km-sized planetesimals and the accretion of mm-cm sized pebbles are typically discussed separately as the main solid accretion mechanisms. We investigate the interplay between the two accretion processes in a disk containing both pebbles and planetesimals for planet formation in general and in the context of giant planet formation specifically. The goal is to disentangle and understand the fundamental interactions that arise in such hybrid pebble-planetesimal models. We combine a simple model of pebble formation and accretion with a global model of planet formation which considers the accretion of planetesimals. We compare synthetic populations of planets formed in disks composed of different amounts of pebbles and 600 meter sized planetesimals. On a system-level, we study the formation pathway of giant planets in these disks. We find that, in hybrid disks containing both pebbles and planetesimals, the formation of giant planets is strongly suppressed whereas in a pebbles-only or planetesimals-only scenario, giant planets can form. We identify the heating associated with the accretion of up to 100 km sized planetesimals after the pebble accretion period to delay the runaway gas accretion of massive cores. Coupled with strong inward type-I migration acting on these planets, this results in close-in icy sub-Neptunes originating from the outer disk. We conclude that, in hybrid pebble-planetesimal scenarios, the late accretion of planetesimals is a critical factor in the giant planet formation process and that inward migration is more efficient for planets in increasingly pebble dominated disks.

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A. Kessler and Y. Alibert
Wed, 26 Apr 23
5/62

Comments: Accepted for publication in A&A, 14 pages, 11 figures

Population study on MHD wind-driven disc evolution — Confronting theory and observation [EPA]

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http://arxiv.org/abs/2304.12380


Context. Current research has established magnetised disc winds as a promising way of driving accretion in protoplanetary discs. Aims. We investigate the evolution of large protoplanetary disc populations under the influence of magnetically driven disc winds as well as internal and external photoevaporation. We aim to constrain magnetic disc wind models through comparisons with observations. Methods. We ran 1D vertically integrated evolutionary simulations for low-viscosity discs, including magnetic braking and various outflows. The initial conditions were varied and chosen to produce populations that are representative of actual disc populations inferred from observations. We then compared the observables from the simulations (e.g. stellar accretion rate, disc mass evolution, disc lifetime, etc.) with observational data. Results. Our simulations show that to reach stellar accretion rates comparable to those found by observations $\sim 10^{-8}\mathrm{M}_\odot / \mathrm{yr}$, it is necessary to have access not only to strong magnetic torques, but weak magnetic winds as well. The presence of a strong magnetic disc wind, in combination with internal photoevaporation, leads to the rapid opening of an inner cavity early on, allowing the stellar accretion rate to drop while the disc is still massive. Furthermore, our model supports the notion that external photoevaporation via the ambient far-ultraviolet radiation of surrounding stars is a driving force in disc evolution and could potentially exert a strong influence on planetary formation. Conclusions. Our disc population syntheses show that for a subset of magnetohydrodynamic wind models (weak disc wind, strong torque), it is possible to reproduce important statistical observational constraints. The magnetic disc wind paradigm thus represents a novel and appealing alternative to the classical $\alpha$-viscosity scenario.

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J. Weder, C. Mordasini and A. Emsenhuber
Wed, 26 Apr 23
9/62

Comments: Accepted for publication in A&A

Giants are bullies: how their growth influences systems of inner sub-Neptunes and super-Earths [EPA]

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http://arxiv.org/abs/2304.12758


Observations point to a correlation between outer giants and inner sub-Neptunes, unexplained by simulations so far. We utilize N-body simulations including pebble and gas accretion as well as planetary migration to investigate how the gas accretion rates influence the formation of systems of inner sub-Neptunes and outer gas giants as well as the eccentricity distribution of the outer giant planets. Less efficient envelope contraction rates allow a more efficient formation of systems with inner sub-Neptunes and outer giants. This is caused by the fact that the cores formed in the inner disc are too small to accrete large envelopes and only cores growing in the outer disc can become giants. As a result, instabilities between the outer giant planets do not necessarily destroy the inner systems of sub-Neptunes unlike simulations where giant planets can form closer in. Our simulations show that up to 50% of the systems of cold Jupiters could have inner sub-Neptunes, in agreement with observations. Our simulations show a good agreement with the eccentricity distribution of giants, even though we find a slight mismatch to the mass and semi-major axes distributions. Synthetic transit observations of the inner systems (r<0.7 AU) reveal an excellent match to the Kepler observations, where our simulations match the period ratios of adjacent planet pairs. Thus, the breaking the chains model for super-Earth and sub-Neptune formation remains consistent with observations even when outer giant planets are present. However, simulations with outer giant planets produce more systems with mostly only one inner planet and with larger eccentricities, in contrast to simulations without outer giants. We thus predict that systems with truly single close-in planets are more likely to host outer gas giants and we consequently suggest RV follow-up observations of these systems to constrain the formation pathway.

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B. Bitsch and A. Izidoro
Wed, 26 Apr 23
18/62

Comments: 21 pages, 17 figures, accepted for publication by A&A

Steeper Scattered Disks Buckle Faster [EPA]

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http://arxiv.org/abs/2304.12366


Disks of low-mass bodies scattered by giant planets to large semi-major axis and constant periapsis orbits are vulnerable to a buckling instability. This instability exponentially grows orbital inclinations, raises periapsis distances, and coherently tilts orbits resulting in clustering of arguments of periapsis. The dynamically hot system is then susceptible to the formation of a lopsided mode. Here we show that the timescale of the buckling instability decreases as the radial surface density of the population becomes more centrally dense, i.e., steeper scattered disks buckle faster. Accounting for differential apsidal precession driven by giant planets, we find that $\sim!10\,M_\oplus$ is sufficient for a primordial scattered disk in the trans-Neptunian region to have been unstable if $dN \propto a^{-2.5} da$.

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A. Zderic and A. Madigan
Wed, 26 Apr 23
20/62

Comments: 5 pages, 4 figures, accepted by ApJL

Inner edges of planetesimal belts: collisionally eroded or truncated? [EPA]

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http://arxiv.org/abs/2304.12337


The radial structure of debris discs can encode important information about their dynamical and collisional history. In this paper we present a 3-phase analytical model to analyse the collisional evolution of solids in debris discs, focusing on their joint radial and temporal dependence. Consistent with previous models, we find that as the largest planetesimals reach collisional equilibrium in the inner regions, the surface density of dust and solids becomes proportional to $\sim r^{2}$ within a certain critical radius. We present simple equations to estimate the critical radius and surface density of dust as a function of the maximum planetesimal size and initial surface density in solids (and vice versa). We apply this model to ALMA observations of 7 wide debris discs. We use both parametric and non-parametric modelling to test if their inner edges are shallow and consistent with collisional evolution. We find that 4 out of 7 have inner edges consistent with collisional evolution. Three of these would require small maximum planetesimal sizes below 10 km, with HR 8799’s disc potentially lacking solids larger than a few centimeters. The remaining systems have inner edges that are much sharper, which requires maximum planetesimal sizes $\gtrsim10$ km. Their sharp inner edges suggest they could have been truncated by planets, which JWST could detect. In the context of our model, we find that the 7 discs require surface densities below a Minimum Mass Solar Nebula, avoiding the so-called disc mass problem. Finally, during the modelling of HD 107146 we discover that its wide gap is split into two narrower ones, which could be due to two low-mass planets formed within the disc.

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A. Blanco, S. Marino, L. Matrà, et. al.
Wed, 26 Apr 23
40/62

Comments: Accepted for publication in MNRAS, 21 pages, 11 figures

Warm giant exoplanet characterisation: current state, challenges and outlook [EPA]

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http://arxiv.org/abs/2304.12782


The characterisation of giant exoplanets is crucial to constrain giant planet formation and evolution theory and for putting the solar-system’s giant planets in perspective. Typically, mass-radius (M-R) measurements of moderately irradiated warm Jupiters are used to estimate the planetary bulk composition, which is an essential quantity for constraining giant planet formation, evolution and structure models. The successful launch of the James Webb Space Telescope (JWST) and the upcoming ARIEL mission open a new era in giant exoplanet characterisation as atmospheric measurements provide key information on the composition and internal structure of giant exoplanets. In this review, we discuss how giant planet evolution models are used to infer the planetary bulk composition, and the connection between the compositions of the interior and atmosphere. We identify the important theoretical uncertainties in evolution models including the equations of state, atmospheric models, chemical composition, interior structure and main energy transport processes. Nevertheless, we show that that atmospheric measurements by JWST and ARIEL and the accurate determination of stellar ages by PLATO can significantly reduce the degeneracy in the inferred bulk composition. Furthermore, we discuss the importance of evolution models for the characterisation of direct-imaged planets. We conclude that giant planet theory has a critical role in the interpretation of observation and emphasise the importance of advancing giant planet theory.

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S. Müller and R. Helled
Wed, 26 Apr 23
45/62

Comments: 15 pages, 2 figures, accepted for publication in Frontiers in Astronomy and Space Sciences

Enabling Exoplanet Demographics Studies with Standardized Exoplanet Survey Meta-Data [IMA]

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http://arxiv.org/abs/2304.12442


Goal 1 of the National Academies of Science, Engineering and Mathematics Exoplanet Science Strategy is “to understand the formation and evolution of planetary systems as products of the process of star formation, and characterize and explain the diversity of planetary system architectures, planetary compositions, and planetary environments produced by these processes”, with the finding that “Current knowledge of the demographics and characteristics of planets and their systems is substantially incomplete.” One significant roadblock to our ongoing efforts to improve our demographics analyses is the lack of comprehensive meta-data accompanying published exoplanet surveys. The Exoplanet Program Analysis Group (ExoPAG) Science Interest Group 2: Exoplanet Demographics has prepared this document to provide guidance to survey architects, authors, referees and funding agencies as to the most valuable such data products for five different exoplanet detection techniques – transit, radial velocity, direct imaging, microlensing and astrometry. We find that making these additional data easily available would greatly enhance the community’s ability to perform robust, reproducible demographics analyses, and make progress on achieving the most important goals identified by the exoplanet and wider astronomical community.

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P. Group, 2. Demographics, J. Christiansen, et. al.
Wed, 26 Apr 23
48/62

Comments: 21 pages, final report after community feedback addressed

Bioverse: A Comprehensive Assessment of the Capabilities of Extremely Large Telescopes to Probe Earth-like O$_\mathrm{2}$ Levels in Nearby Transiting Habitable Zone Exoplanets [EPA]

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http://arxiv.org/abs/2304.12490


Molecular oxygen is a strong indicator of life on Earth, and may indicate biological processes on exoplanets too. Recent studies proposed that Earth-like O$\mathrm{2}$ levels might be detectable on nearby exoplanets using high-resolution spectrographs on future extremely large telescopes (ELTs). However, these studies did not consider constraints like relative velocities, planet occurrence rates, and target observability. We expanded on past studies by creating a homogeneous catalog of 286,391 main-sequence stars within 120 pc using Gaia DR3, and used the Bioverse framework to simulate the likelihood of finding nearby transiting Earth analogs. We also simulated a survey of M dwarfs within 20 pc accounting for $\eta{\oplus}$ estimates, transit probabilities, relative velocities, and target observability to determine how long ELTs and theoretical 50-100 meter ground-based telescopes need to observe to probe for Earth-like O$\mathrm{2}$ levels with an $R=100,000$ spectrograph. This would only be possible within 50 years for up to $\sim$21% of nearby M dwarf systems if a suitable transiting habitable zone Earth-analog was discovered, assuming signals from every observable partial transit from each ELT can be combined. If so, Earth-like O$\mathrm{2}$ levels could be detectable on TRAPPIST-1 d-g within 16 to 55 years, respectively, and about half that time with an $R=500,000$ spectrograph. These results have important implications for whether ELTs can survey nearby habitable zone Earth analogs for O$_\mathrm{2}$ via transmission spectroscopy. Our work provides the most comprehensive assessment to date of the ground-based capabilities to search for life beyond the solar system.

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K. Hardegree-Ullman, D. Apai, G. Bergsten, et. al.
Wed, 26 Apr 23
54/62

Comments: 30 pages, 14 figures, 8 tables. Revised and resubmitted to AJ after a favorable referee report

The shared evaporation history of three sub-Neptunes spanning the radius-period valley of a Hyades star [EPA]

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http://arxiv.org/abs/2304.12705


We model the evaporation histories of the three planets around K2-136, a K-dwarf in the Hyades open cluster with an age of 700 Myr. The star hosts three transiting planets, with radii of 1.0, 3.0 and 1.5 Earth radii, where the middle planet lies above the radius-period valley and the inner and outer planets are below. We use an XMM-Newton observation to measure the XUV radiation environment of the planets, finding that the X-ray activity of K2-136 is lower than predicted by models but typical of similar Hyades members. We estimate the internal structure of each planet, and model their evaporation histories using a range of structure and atmospheric escape formulations. While the precise X-ray irradiation history of the system may be uncertain, we exploit the fact that the three planets must have shared the same history. We find that the Earth-sized K2-136b is most likely rocky, with any primordial gaseous envelope being lost within a few Myr. The sub-Neptune, K2-136c, has an envelope contributing 1-1.7% of its mass that is stable against evaporation thanks to the high mass of its rocky core, whilst the super-Earth, K2-136d, must have a mass at the upper end of the allowed range in order to retain any of its envelope. Our results are consistent with all three planets beginning as sub-Neptunes that have since been sculpted by atmospheric evaporation to their current states, stripping the envelope from planet b and removing most from planet d whilst preserving planet c above the radius-period valley.

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J. Fernández, P. Wheatley and G. King
Wed, 26 Apr 23
57/62

Comments: Accepted for publication on MNRAS

Orbital Architectures of Kepler Multis From Planet-Planet Scattering [EPA]

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http://arxiv.org/abs/2304.12352


The high-multiplicity exoplanet systems are generally more tightly packed when compared to the solar system. Such compact multi-planet systems are often susceptible to dynamical instability. We investigate the impact of dynamical instability on the final orbital architectures of multi-planet systems using N-body simulations. Our models initially consist of eight planets placed randomly according to a power-law distribution of mutual Hill separations. We find that almost all of our model planetary systems go through at least one phase of dynamical instability, losing at least one planet. The orbital architecture, including the distributions of mutual Hill separations, planetary masses, orbital periods, and period ratios, of the transit-detectable model planetary systems closely resemble those for the multi-planet systems detected by Kepler. We find that without any formation-dependent input, a dynamically active past can naturally reproduce important observed trends including multiplicity-dependent eccentricity distribution, smaller eccentricities for larger planets, and intra-system uniformity. These findings indicate that dynamical instabilities may have played a vital role in the final assembly of sub-Jovian planets.

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T. Ghosh and S. Chatterjee
Wed, 26 Apr 23
61/62

Comments: 12 pages, 13 figures; submitted to MNRAS; comments welcome

Constraining the Origin of Mars via Simulations of Multi-Stage Core Formation [EPA]

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http://arxiv.org/abs/2304.11236


It remains an elusive goal to simultaneously model the astrophysics of Solar System accretion while reproducing the mantle chemistry of more than one inner terrestrial planet. Here, we used a multistage core-mantle differentiation model based on Rubie et al. (2011,2015) to track the formation and composition of Earth and Mars in various Grand Tack formation simulations. Prior studies showed that in order to recreate Earth’s mantle composition, it must grow first from reduced (Fe-metal rich and O-poor) building blocks and then from increasingly oxidized (FeO rich) material. This accretion chemistry occurs when an oxidation gradient exists across the disk so that the innermost solids are reduced and increasingly oxidized material is found at greater heliocentric distances. For a suite of Grand Tack simulations, we investigated whether Earth and Mars can be simultaneously produced by the same oxidation gradient. Our model did not find an oxidation gradient that simultaneously reproduces the mantle composition of Earth and Mars. Due to its small mass and rapid formation, the formation history of Mars-like planets is very stochastic which decreases the likelihood of compatibility with an Earth-producing oxidation gradient in any given realization. To reconcile the accretion history and ideal chemistry of the Mars-like planet with the oxidation gradient of an Earth-producing disk, we determined where in the Earth-producing disk Mars must have formed. We find that the FeO-rich composition of the Martian mantle requires that Mars’ building blocks must originate exterior to 1.0 astronomical units (AU).

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G. Nathan, D. Rubie and S. Jacobson
Tue, 25 Apr 23
11/72

Comments: 20 pages, 7 figures, Accepted for publication at ICARUS 04/2023

Fifteen years of millimeter accuracy lunar laser ranging with APOLLO: data reduction and calibration [IMA]

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http://arxiv.org/abs/2304.11174


The Apache Point Lunar Laser-ranging Operation (APOLLO) has been collecting lunar range measurements for 15 years at millimeter accuracy. The median nightly range uncertainty since 2006 is 1.7 mm. A recently added Absolute Calibration System (ACS), providing an independent assessment of APOLLO system accuracy and the capability to correct lunar range data, revealed a 0.4% systematic error in the calibration of one piece of hardware that has been present for the entire history of APOLLO. Application of ACS-based timing corrections suggests systematic errors are reduced to < 1 mm, such that overall data accuracy and precision are both 1 mm. This paper describes the processing of APOLLO/ACS data that converts photon-by-photon range measurements into the aggregated normal points that are used for physics analyses. Additionally we present methodologies to estimate timing corrections for range data lacking contemporaneous ACS photons, including range data collected prior to installation of the ACS. We also provide access to the full 15-year archive of APOLLO normal points (2006-04-06 to 2020-12-27).

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N. Colmenares, J. Battat, D. Gonzales, et. al.
Tue, 25 Apr 23
23/72

Comments: 23 pages, 9 figures

Lorenz Energy Cycle: Another Way to Understand the Atmospheric Circulation on Tidally Locked Terrestrial Planets [EPA]

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http://arxiv.org/abs/2304.11627


In this study, we employ and modify the Lorenz energy cycle (LEC) framework as another way to understand the atmospheric circulation on tidally locked terrestrial planets. It well describes the atmospheric general circulation in the perspective of energy transformation, involved with several dynamical processes. We find that on rapidly rotating, tidally locked terrestrial planets, mean potential energy (P${\rm M}$) and eddy potential energy (P${\rm E}$) are comparable to those on Earth, as they have similar steep meridional temperature gradients. Mean kinetic energy (K${\rm M}$) and eddy kinetic energy (K${\rm E}$) are larger than those on Earth, related to stronger winds. The two conversion paths, P${\rm M}\rightarrow$P${\rm E}\rightarrow$K${\rm E}$ and P${\rm M}\rightarrow$K${\rm M}\rightarrow$K${\rm E}$, are both efficient. The former is associated with strong baroclinic instabilities, and the latter is associated with Hadley cells. On slowly rotating, tidally locked terrestrial planets, weak temperature gradients in the free atmosphere and strong nightside temperature inversion make P${\rm M}$ and P${\rm E}$ are much smaller than those on Earth. Meanwhile, large day–night surface temperature contrast and small rotation rate make the overturning circulation extend to the globe, so that the main conversion path is P${\rm M}\rightarrow$K${\rm M}\rightarrow$K$_{\rm E}$. This study shows that the LEC analyses improve the understanding of the atmospheric circulation on tidally locked terrestrial planets.

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S. Wang and J. Yang
Tue, 25 Apr 23
27/72

Comments: 25 pages, 16 fugures

Prospects for the characterization of habitable planets [EPA]

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http://arxiv.org/abs/2304.11570


With thousands of exoplanets now identified, the characterization of habitable planets and the potential identification of inhabited ones is a major challenge for the coming decades. We review the current working definition of habitable planets, the upcoming observational prospects for their characterization and present an innovative approach to assess habitability and inhabitation. This integrated method couples for the first time the atmosphere and the interior modeling with the biological activity based on ecosystem modeling. We review here the first applications of the method to asses the likelihood and impact of methanogenesis for Enceladus, primitive Earth, and primitive Mars. Informed by these applications for solar system situations where habitability and inhabitation is questionned, we show how the method can be used to inform the design of future space observatories by considering habitability and inhabitation of Earth-like exoplanets around sun-like stars.

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S. Mazevet, A. Affholder, B. Sauterey, et. al.
Tue, 25 Apr 23
30/72

Comments: 16 pages, 4 figures

WASP-131 b with ESPRESSO I: A bloated sub-Saturn on a polar orbit around a differentially rotating solar-type star [EPA]

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http://arxiv.org/abs/2304.12163


In this paper, we present observations of two high-resolution transit datasets obtained with ESPRESSO of the bloated sub-Saturn planet WASP-131~b. We have simultaneous photometric observations with NGTS and EulerCam. In addition, we utilised photometric lightcurves from {\tess}, WASP, EulerCam and TRAPPIST of multiple transits to fit for the planetary parameters and update the ephemeris. We spatially resolve the stellar surface of WASP-131 utilising the Reloaded Rossiter McLaughlin technique to search for centre-to-limb convective variations, stellar differential rotation, and to determine the star-planet obliquity for the first time. We find WASP-131 is misaligned on a nearly retrograde orbit with a projected obliquity of $\lambda = 162.4\substack{+1.3 \ -1.2}^{\circ}$. In addition, we determined a stellar differential rotation shear of $\alpha = 0.61 \pm 0.06$ and disentangled the stellar inclination ($i_* = 40.9\substack{+13.3 \ -8.5}^{\circ}$) from the projected rotational velocity, resulting in an equatorial velocity of $v_{\rm{eq}} = 7.7\substack{+1.5 \ -1.3}$~km s$^{-1}$. In turn, we determined the true 3D obliquity of $\psi = 123.7\substack{+12.8 \ -8.0}^{\circ}$, meaning the planet is on a perpendicular/polar orbit. Therefore, we explored possible mechanisms for the planetary system’s formation and evolution. Finally, we searched for centre-to-limb convective variations where there was a null detection, indicating that centre-to-limb convective variations are not prominent in this star or are hidden within red noise.

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L. Doyle, H. Cegla, D. Anderson, et. al.
Tue, 25 Apr 23
36/72

Comments: 15 Pages, 10 Figures and 4 Tables Accepted for Publication in MNRAS. arXiv admin note: text overlap with arXiv:2207.10127

Tidal dissipation in stratified and semi-convective regions of giant planets [EPA]

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http://arxiv.org/abs/2304.11898


We study how stably stratified or semi-convective layers alter the tidal dissipation rates associated with the generation of internal waves in planetary interiors. We consider if these layers could contribute to the high rates of tidal dissipation observed for Jupiter and Saturn in our solar system. We use an idealised global spherical Boussinesq model to study the influence of stable stratification and semi-convective layers on tidal dissipation rates. We carry out analytical and numerical calculations considering realistic tidal forcing and measure how the viscous and thermal dissipation rates depend on the parameters relating to the internal stratification profile. We find that the strongly frequency-dependent tidal dissipation rate is highly dependent on the parameters relating to the stable stratification, with strong resonant peaks that align with the internal modes of the system. The locations and sizes of these resonances depend on the form and parameters of the stratification, which we explore both analytically and numerically. Our results suggest that stable stratification can significantly enhance the tidal dissipation in particular frequency ranges. Analytical calculations in the low frequency regime give us scaling laws for the key parameters, including the tidal quality factor $Q’$ due to internal gravity waves. Stably stratified layers can significantly contribute to tidal dissipation in solar and extrasolar giant planets, and we estimate substantial tidal evolution for hot Neptunes. Further investigation is needed to robustly quantify the significance of the contribution in realistic interior models, and to consider the contribution of inertial waves.

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C. Pontin, A. Barker and R. Hollerbach
Tue, 25 Apr 23
40/72

Comments: 29 pages, 17 figures, accepted for publication in ApJ (13th April 2023)

Detection of carbon monoxide's 4.6 micron fundamental band structure in WASP-39b's atmosphere with JWST NIRSpec G395H [EPA]

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http://arxiv.org/abs/2304.11994


Carbon monoxide (CO) is predicted to be the dominant carbon-bearing molecule in giant planet atmospheres, and, along with water, is important for discerning the oxygen and therefore carbon-to-oxygen ratio of these planets. The fundamental absorption mode of CO has a broad double-branched structure composed of many individual absorption lines from 4.3 to 5.1 $\mathrm{\mu}$m, which can now be spectroscopically measured with JWST. Here we present a technique for detecting the rotational sub-band structure of CO at medium resolution with the NIRSpec G395H instrument. We use a single transit observation of the hot Jupiter WASP-39b from the JWST Transiting Exoplanet Community Early Release Science (JTEC ERS) program at the native resolution of the instrument ($R \,{\sim} 2700$) to resolve the CO absorption structure. We robustly detect absorption by CO, with an increase in transit depth of 264 $\pm$ 68 ppm, in agreement with the predicted CO contribution from the best-fit model at low resolution. This detection confirms our theoretical expectations that CO is the dominant carbon-bearing molecule in WASP-39b’s atmosphere, and further supports the conclusions of low C/O and super-solar metallicities presented in the JTEC ERS papers for WASP-39b.

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D. Grant, J. Lothringer, H. Wakeford, et. al.
Tue, 25 Apr 23
42/72

Comments: 11 pages, 5 figures, accepted for publication in ApJL

The Gaia-ESO Survey: Empirical estimates of stellar ages from lithium equivalent widths (EAGLES) [SSA]

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http://arxiv.org/abs/2304.12197


We present an empirical model of age-dependent photospheric lithium depletion, calibrated using a large, homogeneously-analysed sample of 6200 stars in 52 open clusters, with ages from 2–6000 Myr and $-0.3<{\rm [Fe/H}]<0.2$, observed in the Gaia-ESO spectroscopic survey. The model is used to obtain age estimates and posterior age probability distributions from measurements of the Li I 6708A equivalent width for individual (pre) main sequence stars with $3000 < T_{\rm eff}/{\rm K} <6500$, a domain where age determination from the HR diagram is either insensitive or highly model-dependent. In the best cases, precisions of 0.1 dex in log age are achievable; even higher precision can be obtained for coeval groups and associations where the individual age probabilities of their members can be combined. The method is validated on a sample of exoplanet-hosting young stars, finding agreement with claimed young ages for some, but not others. We obtain better than 10 per cent precision in age, and excellent agreement with published ages, for seven well-studied young moving groups. The derived ages for young clusters ($<1$ Gyr) in our sample are also in good agreement with their training ages, and consistent with several published, model-insensitive lithium depletion boundary ages. For older clusters there remain systematic age errors that could be as large as a factor of two. There is no evidence to link these errors to any strong systematic metallicity dependence of (pre) main sequence lithium depletion, at least in the range $-0.29 < {\rm [Fe/H]} < 0.18$. Our methods and model are provided as software — “Empirical AGes from Lithium Equivalent widthS” (EAGLES).

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R. Jeffries, R. Jackson, N. Wright, et. al.
Tue, 25 Apr 23
55/72

Comments: Accepted for publication in Monthly Notices of the Royal Astronomical Society

New compound and hybrid binding energy sputter model for modeling purposes in agreement with experimental data [EPA]

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http://arxiv.org/abs/2304.12048


Rocky planets and moons experiencing solar wind sputtering are continuously supplying their enveloping exosphere with ejected neutral atoms. To understand the quantity and properties of the ejecta, well established Binary Collision Approximation Monte Carlo codes like TRIM with default settings are used predominantly. Improved models such as SDTrimSP have come forward and together with new experimental data the underlying assumptions have been challenged. We introduce a hybrid model, combining the previous surface binding approach with a new bulk binding model akin to Hofs\”ass & Stegmaier (2023). In addition, we expand the model implementation by distinguishing between free and bound components sourced from mineral compounds such as oxides or sulfides. The use of oxides and sulfides also enables the correct setting of the mass densities of minerals, which was previously limited to the manual setting of individual atomic densities of elements. All of the energies and densities used are thereby based on tabulated data, so that only minimal user input and no fitting of parameters are required. We found unprecedented agreement between the newly implemented hybrid model and previously published sputter yields for incidence angles up to 45{\deg} from surface normal. Good agreement is found for the angular distribution of mass sputtered from enstatite MgSiO$_3$ compared to latest experimental data. Energy distributions recreate trends of experimental data of oxidized metals. Similar trends are to be expected from future mineral experimental data. The model thus serves its purpose of widespread applicability and ease of use for modelers of rocky body exospheres.

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N. Jäggi, A. Mutzke, H. Biber, et. al.
Tue, 25 Apr 23
57/72

Comments: 23 pages, 6 figures, 3 tables

GJ3470-d and GJ3470-e: Discovery of Co-Orbiting Exoplanets in a Horseshoe Exchange Orbit [EPA]

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http://arxiv.org/abs/2304.11769


We report the discovery of a pair of exoplanets co-orbiting the red dwarf star GJ3470. The larger planet, GJ3470-d, was observed in a 14.9617-days orbit and the smaller planet, GJ3470-e, in a 14.9467-days orbit. GJ3470-d is sub-Jupiter size with a 1.4% depth and a duration of 3 hours, 4 minutes. The smaller planet, GJ3470-e, currently leads the larger planet by approximately 1.146-days and is extending that lead by about 7.5-minutes (JD 0.0052) per orbital cycle. It has an average depth of 0.5% and an average duration of 3 hours, 2 minutes. The larger planet, GJ3470-d, has been observed on seven separate occasions over a 3-year period, allowing for a very precise orbital period calculation. The last transit was observed by three separate observatories in Oklahoma and Arizona. The smaller planet, GJ3470-e, has been observed on five occasions over 2-years. Our data appears consistent with two exoplanets in a Horseshoe Exchange orbit. When confirmed, these will be the second and third exoplanets discovered and characterized by amateur astronomers without professional data or assistance. It will also be the first ever discovery of co-orbiting exoplanets in a Horseshoe Exchange orbit.

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P. Scott, J. Taylor, L. Beatty, et. al.
Tue, 25 Apr 23
60/72

Comments: 10 pages, 4 figures, 3 tables

Prediction of the collisions of meteoroids originating in comet 21P/Giacobini-Zinner with the Mercury, Venus, and Mars [EPA]

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http://arxiv.org/abs/2304.11935


After the prediction of meteor showers in the Earth’s atmosphere caused by the particles originating in the nucleus of comet 21P/Giacobini-Zinner, we went on with the prediction of showers on the other three terrestrial planets. Based on our modeling of theoretical stream of the parent comet, we predicted several related meteorite (on Mercury) or meteor (on Venus and Mars) showers. There occurred the filaments, in the stream, with the particles coming to each planet from a similar direction. We found that this is a consequence of the specific distribution of argument of perihelion (peaked close to the value of $180^{\circ}$) and longitude of ascending node of the stream, and that the particles collide with each planet in an arc of their orbits being close to perihelion.

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D. Tomko and L. Neslušan
Tue, 25 Apr 23
71/72

Comments: 8 pages (3 figures included), 6 tables (in appendix), submitted to Icarus

There's more to life than O$_2$: Simulating the detectability of a range of molecules for ground-based high-resolution spectroscopy of transiting terrestrial exoplanets [EPA]

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http://arxiv.org/abs/2304.10683


Within the next decade, atmospheric O$_2$ on Earth-like M dwarf planets may be accessible with visible–near-infrared, high spectral resolution extremely large ground-based telescope (ELT) instruments. However, the prospects for using ELTs to detect environmental properties that provide context for O$_2$ have not been thoroughly explored. Additional molecules may help indicate planetary habitability, rule out abiotically generated O$_2$, or reveal alternative biosignatures. To understand the accessibility of environmental context using ELT spectra, we simulate high-resolution transit transmission spectra of previously-generated evolved terrestrial atmospheres. We consider inhabited pre-industrial and Archean Earth-like atmospheres, and lifeless worlds with abiotic O$_2$ buildup from CO$_2$ and H$_2$O photolysis. All atmospheres are self-consistent with M2V–M8V dwarf host stars. Our simulations include explicit treatment of systematic and telluric effects to model high-resolution spectra for GMT, TMT, and E-ELT configurations for systems 5 and 12 pc from Earth. Using the cross-correlation technique, we determine the detectability of major species in these atmospheres: O$_2$, O$_3$, CH$_4$, CO$_2$, CO, H$_2$O, and C$_2$H$_6$. Our results suggest that CH$_4$ and CO$_2$ are the most accessible molecules for terrestrial planets transiting a range of M dwarf hosts using an E-ELT, TMT, or GMT sized telescope, and that the O$_2$ NIR and H$_2$O 0.9 $\mu$m bands may also be accessible with more observation time. Although this technique still faces considerable challenges, the ELTs will provide access to the atmospheres of terrestrial planets transiting earlier-type M-dwarf hosts that may not be possible using JWST.

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M. Currie, V. Meadows and K. Rasmussen
Mon, 24 Apr 23
14/41

Comments: Accepted for publication in The Planetary Science Journal

Exploring the stellar surface phenomena of WASP-52 and HAT-P-30 with ESPRESSO [EPA]

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http://arxiv.org/abs/2304.11022


We analyse spectroscopic and photometric transits of the hot Jupiters WASP-52b and HAT-P30b obtained with ESPRESSO, Eulercam and NGTS for both targets, and additional TESS data for HAT-P-30. Our goal is to update the system parameters and refine our knowledge of the host star surfaces. For WASP-52, the companion planet has occulted starspots in the past, and as such our aim was to use the reloaded Rossiter-McLaughlin technique to directly probe its starspot properties. Unfortunately, we find no evidence for starspot occultations in the datasets herein. Additionally, we searched for stellar surface differential rotation (DR) and any centre-to-limb variation (CLV) due to convection, but return a null detection of both. This is unsurprising for WASP-52, given its relatively cool temperature, high magnetic activity (which leads to lower CLV), and projected obliquity near 0 degrees (meaning the transit chord is less likely to cross several stellar latitudes). For HAT-P-30, this result was more surprising given its hotter effective temperature, lower magnetic field, and high projected obliquity (near 70 degrees). To explore the reasons behind the null DR and CLV detection for HAT-P-30, we simulated a variety of scenarios. We find that either the CLV present on HAT-P-30 is below the solar level or the presence of DR prevents a CLV detection given the precision of the data herein. A careful treatment of both DR and CLV is required, especially for systems with high impact factors, due to potential degeneracies between the two. Future observations and/or a sophisticated treatment of the red noise present in the data (likely due to granulation) is required to refine the DR and CLV for these particular systems; such observations would also present another opportunity to try to examine starspots on WASP-52.

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H. Cegla, N. Roguet-Kern, M. Lendl, et. al.
Mon, 24 Apr 23
19/41

Comments: 11 pages main text, 8 figures; accepted for publication in A&A

Showers with both northern and southern solutions [EPA]

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http://arxiv.org/abs/2304.10794


Meteoroids of a low-inclination stream hit the Earth arriving from a direction near the ecliptic. The radiant area of stream like this is often divided into two parts: one is situated northward and the other southward of the ecliptic. In other words, two showers are caused by such a stream. Well-known examples of such showers are the Northern Taurids, #17, and Southern Taurids, #2, or the Northern $\delta$-Aquariids, #26, and Southern $\delta$-Aquariids, #5. While the meteoroids of the northern shower collide with the Earth in the descending node, those of the southern shower collide with our planet in the ascending node of their orbits. Because of this circumstance and tradition, the northern and southern showers must be distinguished. Unfortunately, this is not always the case with meteor showers listed in the IAU Meteor Data Center (MDC). For the same shower, some authors reported a set of its mean parameters corresponding to the northern shower and other authors to the southern shower. We found eleven such cases in the MDC. In this paper, we propose corrections of these mis-identifications.

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L. Neslušan, T. Jopek, R. Rudawska, et. al.
Mon, 24 Apr 23
31/41

Comments: Submitted: Planetary and Space Science

Avoiding methane emission rate underestimates when using the divergence method [CL]

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http://arxiv.org/abs/2304.10303


Methane is a powerful greenhouse gas, and a primary target for mitigating climate change in the short-term future due to its relatively short atmospheric lifetime and greater ability to trap heat in Earth’s atmosphere compared to carbon dioxide. Top-down observations of atmospheric methane are possible via drone and aircraft surveys as well as satellites such as the TROPOspheric Monitoring Instrument (TROPOMI). Recent work has begun to apply the divergence method to produce regional methane emission rate estimates. Here we show that spatially incomplete observations of methane can produce negatively biased time-averaged regional emission rate estimates via the divergence method, but that this effect can be counteracted by adopting a procedure in which daily advective fluxes of methane are time-averaged before the divergence method is applied. Using such a procedure with TROPOMI methane observations, we calculate yearly Permian emission rates of 3.1, 2.4 and 2.7 million tonnes per year for the years 2019 through 2021. We also show that highly-resolved plumes of methane can have negatively biased estimated emission rates by the divergence method due to the presence of turbulent diffusion in the plume, but this is unlikely to affect regional methane emission budgets constructed from TROPOMI observations of methane. The results from this work are expected to provide useful guidance for future implementations of the divergence method for emission rate estimation from satellite data – be it for methane or other gaseous species in the atmosphere.

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C. Roberts, R. IJzermans, D. Randell, et. al.
Fri, 21 Apr 23
1/60

Comments: 17 pages, 10 figures, submitted to Environmental Research Letters

Exoplanet Nodal Precession Induced by Rapidly Rotating Stars: Impacts on Transit Probabilities and Biases [EPA]

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http://arxiv.org/abs/2304.09890


For the majority of short period exoplanets transiting massive stars with radiative envelopes, the spin angular momentum of the host star is greater than the planetary orbital angular momentum. In this case, the orbits of the planets will undergo nodal precession, which can significantly impact the probability that the planets transit their parent star. In particular, for some combinations of the spin-orbit angle $\psi$ and the inclination of the stellar spin $i_*$, all such planets will eventually transit at some point over the duration of their precession period. Thus, as the time over which the sky has been monitored for transiting planets increases, the frequency of planets with detectable transits will increase, potentially leading to biased estimates of exoplanet occurrence rates, especially orbiting more massive stars. Furthermore, due to the dependence of the precession period on orbital parameters such as spin-orbit misalignment, the observed distributions of such parameters may also be biased. We derive the transit probability of a given exoplanet in the presence of nodal precession induced by a rapidly spinning host star. We find that the effect of nodal precession has already started to become relevant for some short-period planets, i.e., Hot Jupiters, orbiting massive stars, by increasing transit probabilities by of order a few percent for such systems within the original $Kepler$ field. We additionally derive simple expressions to describe the time evolution of the impact parameter $b$ for applicable systems, which should aid in future investigations of exoplanet nodal precession and spin-orbit alignment.

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A. Stephan and B. Gaudi
Fri, 21 Apr 23
8/60

Comments: 9 pages, 5 figures, accepted for publication in ApJ

Constraints on Magnetic Braking from the G8 Dwarf Stars 61 UMa and $τ$ Cet [SSA]

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http://arxiv.org/abs/2304.09896


During the first half of their main-sequence lifetimes, stars rapidly lose angular momentum to their magnetized winds, a process known as magnetic braking. Recent observations suggest a substantial decrease in the magnetic braking efficiency when stars reach a critical value of the Rossby number, the stellar rotation period normalized by the convective overturn timescale. Cooler stars have deeper convection zones with longer overturn times, reaching this critical Rossby number at slower rotation rates. The nature and timing of the transition to weakened magnetic braking has previously been constrained by several solar analogs and two slightly hotter stars. In this Letter, we derive the first direct constraints from stars cooler than the Sun. We present new spectropolarimetry of the old G8 dwarf $\tau$ Cet from the Large Binocular Telescope, and we reanalyze a published Zeeman Doppler image of the younger G8 star 61 UMa, yielding the large-scale magnetic field strengths and morphologies. We estimate mass-loss rates using archival X-ray observations and inferences from Ly$\alpha$ measurements, and we adopt other stellar properties from asteroseismology and spectral energy distribution fitting. The resulting calculations of the wind braking torque demonstrate that the rate of angular momentum loss drops by a factor of 300 between the ages of these two stars (1.4-9 Gyr), well above theoretical expectations. We summarize the available data to help constrain the value of the critical Rossby number, and we identify a new signature of the long-period detection edge in recent measurements from the Kepler mission.

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T. Metcalfe, K. Strassmeier, I. Ilyin, et. al.
Fri, 21 Apr 23
15/60

Comments: ApJ Letters (accepted), 6 pages including 3 figures and 1 table. Python code is available at this https URL

Giant planet engulfment by evolved giant stars: light curves, asteroseismology, and survivability [EPA]

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http://arxiv.org/abs/2304.09882


About ten percent of Sun-like ($1$-$2 M_\odot$) stars will engulf a $1$-$10 M_{\rm J}$ planet as they expand during the red giant branch (RGB) or asymptotic giant branch (AGB) phase of their evolution. Once engulfed, these planets experience a strong drag force in the star’s convective envelope and spiral inward, depositing energy and angular momentum. For these mass ratios, the inspiral takes $\sim 10$-$10^{2}$ years ($\sim 10^{2}$-$10^{3}$ orbits); the planet undergoes tidal disruption at a radius of $\sim R_\odot$. We use the Modules for Experiments in Stellar Astrophysics (MESA) software instrument to track the stellar response to the energy deposition while simultaneously evolving the planetary orbit. For RGB stars, as well as AGB stars with $M_{\rm p} \lesssim 5 M_{\rm J}$ planets, the star responds quasistatically but still brightens measurably on a timescale of years. In addition, asteroseismic indicators, such as the frequency spacing or rotational splitting, differ before and after engulfment. For AGB stars, engulfment of a $M_{\rm p} \gtrsim 5 M_{\rm J}$ planet drives supersonic expansion of the envelope, causing a bright, red, dusty eruption similar to a “luminous red nova.” Based on the peak luminosity, color, duration, and expected rate of these events, we suggest that engulfment events on the AGB could be a significant fraction of low-luminosity red novae in the Galaxy. We do not find conditions where the envelope is ejected prior to the planet’s tidal disruption, complicating the interpretation of short-period giant planets orbiting white dwarfs as survivors of common-envelope evolution.

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C. O’Connor, L. Bildsten, M. Cantiello, et. al.
Fri, 21 Apr 23
36/60

Comments: 24 pages, 11 figures, 1 table. Submitted to AAS Journals; revised after initial review. Comments welcome

Jupiter Science Enabled by ESA's Jupiter Icy Moons Explorer [EPA]

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http://arxiv.org/abs/2304.10229


ESA’s Jupiter Icy Moons Explorer (JUICE) will provide a detailed investigation of the Jovian system in the 2030s, combining a suite of state-of-the-art instruments with an orbital tour tailored to maximise observing opportunities. We review the Jupiter science enabled by the JUICE mission, building on the legacy of discoveries from the Galileo, Cassini, and Juno missions, alongside ground- and space-based observatories. We focus on remote sensing of the climate, meteorology, and chemistry of the atmosphere and auroras from the cloud-forming weather layer, through the upper troposphere, into the stratosphere and ionosphere. The Jupiter orbital tour provides a wealth of opportunities for atmospheric and auroral science: global perspectives with its near-equatorial and inclined phases, sampling all phase angles from dayside to nightside, and investigating phenomena evolving on timescales from minutes to months. The remote sensing payload spans far-UV spectroscopy (50-210 nm), visible imaging (340-1080 nm), visible/near-infrared spectroscopy (0.49-5.56 $\mu$m), and sub-millimetre sounding (near 530-625\,GHz and 1067-1275\,GHz). This is coupled to radio, stellar, and solar occultation opportunities to explore the atmosphere at high vertical resolution; and radio and plasma wave measurements of electric discharges in the Jovian atmosphere and auroras. Cross-disciplinary scientific investigations enable JUICE to explore coupling processes in giant planet atmospheres, to show how the atmosphere is connected to (i) the deep circulation and composition of the hydrogen-dominated interior; and (ii) to the currents and charged particle environments of the external magnetosphere. JUICE will provide a comprehensive characterisation of the atmosphere and auroras of this archetypal giant planet.

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L. Fletcher, T. Cavalié, D. Grassi, et. al.
Fri, 21 Apr 23
45/60

Comments: 83 pages, 24 figures, submitted to Space Science Reviews special issue on ESA’s JUICE mission

Constellations of co-orbital planets: horseshoe dynamics, long-term stability, transit timing variations, and potential as SETI beacons [EPA]

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http://arxiv.org/abs/2304.09209


Co-orbital systems contain two or more bodies sharing the same orbit around a planet or star. The best-known flavors of co-orbital systems are tadpoles (in which two bodies’ angular separations oscillate about the L4/L5 Lagrange points $60^\circ$ apart) and horseshoes (with two bodies periodically exchanging orbital energy to trace out a horseshoe shape in a co-rotating frame). Here, we use N-body simulations to explore the parameter space of many-planet horseshoe systems. We show that up to 24 equal-mass, Earth-mass planets can share the same orbit at 1 au, following a complex pattern in which neighboring planets undergo horseshoe oscillations. We explore the dynamics of horseshoe constellations, and show that they can remain stable for billions of years and even persist through their stars’ post-main sequence evolution. With sufficient observations, they can be identified through their large-amplitude, correlated transit timing variations. Given their longevity and exotic orbital architectures, horseshoe constellations may represent potential SETI beacons.

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S. Raymond, D. Veras, M. Clement, et. al.
Thu, 20 Apr 23
2/57

Comments: 10 pages, 10 figures. Published in MNRAS. YouTube playlist with animations of horseshoe constellation systems here: this https URL . Blog post here: this https URL