The magnetic field and multiple planets of the young dwarf AU~Mic [SSA]

http://arxiv.org/abs/2304.09642


In this paper we present an analysis of near-infrared spectropolarimetric and velocimetric data of the young M dwarf AU Mic, collected with SPIRou at the Canada-France-Hawaii telescope from 2019 to 2022, mostly within the SPIRou Legacy Survey. With these data, we study the large- and small-scale magnetic field of AU Mic, detected through the unpolarized and circularly-polarized Zeeman signatures of spectral lines. We find that both are modulated with the stellar rotation period (4.86 d), and evolve on a timescale of months under differential rotation and intrinsic variability. The small-scale field, estimated from the broadening of spectral lines, reaches $2.61\pm0.05$ kG. The large-scale field, inferred with Zeeman-Doppler imaging from Least-Squares Deconvolved profiles of circularly-polarized and unpolarized spectral lines, is mostly poloidal and axisymmetric, with an average intensity of $550\pm30$ G. We also find that surface differential rotation, as derived from the large-scale field, is $\simeq$30% weaker than that of the Sun. We detect the radial velocity (RV) signatures of transiting planets b and c, although dwarfed by activity, and put an upper limit on that of candidate planet d, putatively causing the transit-timing variations of b and c. We also report the detection of the RV signature of a new candidate planet (e) orbiting further out with a period of $33.39\pm0.10$ d, i.e., near the 4:1 resonance with b. The RV signature of e is detected at 6.5$\sigma$ while those of b and c show up at $\simeq$4$\sigma$, yielding masses of $10.2^{+3.9}{-2.7}$ and $14.2^{+4.8}{-3.5}$ Earth masses for b and c, and a minimum mass of $35.2^{+6.7}_{-5.4}$ Earth masses for e.

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D. JF, C. PI, F. B, et. al.
Thu, 20 Apr 23
5/57

Comments: MNRAS, in press (20 pages and 12 figures + 9 pages of supplementary material)

Survival and dynamics of rings of co-orbital planets under perturbations [EPA]

http://arxiv.org/abs/2304.09210


In co-orbital planetary systems, two or more planets share the same orbit around their star. Here we test the dynamical stability of co-orbital rings of planets perturbed by outside forces. We test two setups: i) ‘stationary’ rings of planets that, when unperturbed, remain equally-spaced along their orbit; and ii) horseshoe constellation systems, in which planets are continually undergoing horseshoe librations with their immediate neighbors. We show that a single rogue planet crossing the planets’ orbit more massive than a few lunar masses (0.01-0.04 Earth masses) systematically disrupts a co-orbital ring of 6, 9, 18, or 42 Earth-mass planets located at 1 au. Stationary rings are more resistant to perturbations than horseshoe constellations, yet when perturbed they can transform into stable horseshoe constellation systems. Given sufficient time, any co-orbital ring system will be perturbed into either becoming a horseshoe constellation or complete destabilization.

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S. Raymond, D. Veras, M. Clement, et. al.
Thu, 20 Apr 23
6/57

Comments: 5 pages, 4 figures. Re-submitted to MNRAS. Blog post about co-orbital constellations here: this https URL

Two super-Earths at the edge of the habitable zone of the nearby M dwarf TOI-2095 [EPA]

http://arxiv.org/abs/2304.09220


The main scientific goal of TESS is to find planets smaller than Neptune around stars bright enough to allow further characterization studies. Given our current instrumentation and detection biases, M dwarfs are prime targets to search for small planets that are in (or nearby) the habitable zone of their host star. Here we use photometric observations and CARMENES radial velocity measurements to validate a pair of transiting planet candidates found by TESS. The data was fitted simultaneously using a Bayesian MCMC procedure taking into account the stellar variability present in the photometric and spectroscopic time series. We confirm the planetary origin of the two transiting candidates orbiting around TOI-2095 (TIC 235678745). The star is a nearby M dwarf ($d = 41.90 \pm 0.03$ pc, $T_{\rm eff} = 3759 \pm 87$ K, $V = 12.6$ mag) with a stellar mass and radius of $M_\star = 0.44 \pm 0.02 \; M_\odot$ and $R_\star = 0.44 \pm 0.02 \; R_\odot$, respectively. The planetary system is composed of two transiting planets: TOI-2095b with an orbital period of $P_b = 17.66484 \pm (7\times 10^{-5})$ days and TOI-2095c with $P_c = 28.17232 \pm (14\times 10^{-5})$ days. Both planets have similar sizes with $R_b = 1.25 \pm 0.07 \; R_\oplus$ and $R_c = 1.33 \pm 0.08 \; R_\oplus$ for planet b and c, respectively. We put upper limits on the masses of these objects with $M_b < 4.1 \; M_\oplus$ for the inner and $M_c < 7.4 \; M_\oplus$ for the outer planet (95\% confidence level). These two planets present equilibrium temperatures in the range of 300 – 350 K and are close to the inner edge of the habitable zone of their star.

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F. Murgas, A. Castro-González, E. Pallé, et. al.
Thu, 20 Apr 23
8/57

Comments: Submitted to Astronomy & Astrophysics

The quest for Magrathea planets I: formation of second generation exoplanets around double white dwarfs [EPA]

http://arxiv.org/abs/2304.09204


The evolution of binaries that become double white dwarf (DWD) can cause the ejection of high amounts of dust and gas. Such material can give rise to circumbinary discs and become the cradle of new planets, yet no studies so far have focused on the formation of circumbinary planets around DWDs. These binaries will be the main sources of gravitational waves (GWs) detectable by the ESA Laser Interferometer Space Antenna (LISA) mission, opening the possibility to detect circumbinary planets around short-period DWDs everywhere in the Milky Way. We investigate the formation of Magrathea planets by simulating multiple planet formation tracks to explore how seeds growing first by pebble accretion, and then by gas accretion, are affected by the disc environments surrounding DWDs. We present both planetary formation tracks taking place in steady-state discs, and formation tracks taking place in discs evolving with time. The time-dependent tracks account for both the disc accretion rate onto the central binary and the disc photoevaporation rate caused by stellar irradiation. Our results show that planetary formation in circumbinary discs around DWDs can be possible. In particular, the extreme planetary formation environment implies three main significant results: (i) the accretion rate and the metallicity of the disc should be high in order to form sub-stellar objects with masses up to 31 M$J$, this is achieved only if planet formation starts soon after the onset of the disc and if first generation seeds are present in the disc; (ii) seeds formed within 0.1 Myr, or within 1 Myr, from the onset of the disc can only produce sub-Neptune and Neptunian planets, unless the disc accommodates first generation seeds with mass 10 M${\oplus}$; (iii) most of the planets are finally located within 1 au from the disc centre, while they are still undergoing the gas accretion phase.

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S. Ledda, C. Danielski and D. Turrini
Thu, 20 Apr 23
9/57

Comments: Accepted for publication in A&A on 05/04/2023, abstract shortened, 28 pages, 11 figures, 14 tables

The two rings of (50000) Quaoar [EPA]

http://arxiv.org/abs/2304.09237


Quaoar is a classical Trans-Neptunian Object (TNO) with an area equivalent diameter of 1,100 km and an orbital semi-major axis of 43.3 astronomical units. Based on stellar occultations observed between 2018 and 2021, an inhomogeneous ring (Q1R, Quaoar’s first ring) was detected around this body. Aims. A new stellar occultation by Quaoar was observed on August 9th, 2022 aiming to improve Quaoar’s shape models and the physical parameters of Q1R while searching for additional material around the body. Methods. The occultation provided nine effective chords across Quaoar, pinning down its size, shape, and astrometric position. Large facilities, such as Gemini North and the Canada-France-Hawaii Telescope (CFHT), were used to obtain high acquisition rates and signal-to-noise ratios. The light curves were also used to characterize the Q1R ring (radial profiles and orbital elements). Results. Quaoar’s elliptical fit to the occultation chords yields the limb with an apparent semi-major axis of $579.5\pm4.0$ km, apparent oblateness of $0.12\pm0.01$, and area-equivalent radius of $543\pm2$ km. Quaoar’s limb orientation is consistent with Q1R and Weywot orbiting in Quaoar’s equatorial plane. The orbital radius of Q1R is refined to a value of $4,057\pm6$ km. The radial opacity profile of the more opaque ring profile follows a Lorentzian shape that extends over 60 km, with a full width at half maximum (FWHM) of $\sim5$ km and a peak normal optical depth of 0.4. Besides the secondary events related to the already reported rings, new secondary events detected during the August 2022 occultation in three different data sets are consistent with another ring around Quaoar with a radius of $2,520\pm20$ km, assuming the ring is circular and co-planar with Q1R. This new ring has a typical width of 10 km and a normal optical depth of $\sim$0.004. Like Q1R, it also lies outside Quaoar’s classical Roche limit.

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C. Pereira, B. Sicardy, B. Morgado, et. al.
Thu, 20 Apr 23
14/57

Comments: Accepted for publication in Astronomy & Astrophysics (18-April-2023). 18 pages, 12 figures

Physical and Surface Properties of Comet Nuclei from Remote Observations [EPA]

http://arxiv.org/abs/2304.09309


We summarize the collective knowledge of physical and surface properties of comet nuclei, focusing on those that are obtained from remote observations. We now have measurements or constraints on effective radius for over 200 comets, rotation periods for over 60, axial ratios and color indices for over 50, geometric albedos for over 25, and nucleus phase coefficients for over 20. The sample has approximately tripled since the publication of Comets II, with IR surveys using Spitzer and NEOWISE responsible for the bulk of the increase in effective radii measurements. Advances in coma morphology studies and long-term studies of a few prominent comets have resulted in meaningful constraints on rotation period changes in nearly a dozen comets, allowing this to be added to the range of nucleus properties studied. The first delay-Doppler radar and visible light polarimetric measurements of comet nuclei have been made since Comets II and are considered alongside the traditional methods of studying nuclei remotely. We use the results from recent in situ missions, notably Rosetta, to put the collective properties obtained by remote observations into context, emphasizing the insights gained into surface properties and the prevalence of highly elongated and/or bilobate shapes. We also explore how nucleus properties evolve, focusing on fragmentation and the likely related phenomena of outbursts and disintegration. Knowledge of these behaviors has been shaped in recent years by diverse sources: high resolution images of nucleus fragmentation and disruption events, the detection of thousands of small comets near the Sun, regular photometric monitoring of large numbers of comets throughout the solar system, and detailed imaging of the surfaces of mission targets. Finally, we explore what advances in the knowledge of the bulk nucleus properties may be enabled in coming years.

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M. Knight, R. Kokotanekova and N. Samarasinha
Thu, 20 Apr 23
33/57

Comments: 43 pages, 6 figures. Chapter in press for the book Comets III, edited by K. Meech and M. Combi, University of Arizona Press

Two Warm Super-Earths Transiting the Nearby M Dwarf TOI-2095 [EPA]

http://arxiv.org/abs/2304.09189


We report the detection and validation of two planets orbiting TOI-2095 (TIC 235678745). The host star is a 3700K M1V dwarf with a high proper motion. The star lies at a distance of 42 pc in a sparsely populated portion of the sky and is bright in the infrared (K=9). With data from 24 Sectors of observation during TESS’s Cycles 2 and 4, TOI-2095 exhibits two sets of transits associated with super-Earth-sized planets. The planets have orbital periods of 17.7 days and 28.2 days and radii of 1.30 and 1.39 Earth radii, respectively. Archival data, preliminary follow-up observations, and vetting analyses support the planetary interpretation of the detected transit signals. The pair of planets have estimated equilibrium temperatures of approximately 400 K, with stellar insolations of 3.23 and 1.73 times that of Earth, placing them in the Venus zone. The planets also lie in a radius regime signaling the transition between rock-dominated and volatile-rich compositions. They are thus prime targets for follow-up mass measurements to better understand the properties of warm, transition radius planets. The relatively long orbital periods of these two planets provide crucial data that can help shed light on the processes that shape the composition of small planets orbiting M dwarfs.

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E. Quintana, E. Gilbert, T. Barclay, et. al.
Thu, 20 Apr 23
37/57

Comments: Submitted to AAS Journals

Saturn's Interior After the Cassini Grand Finale [EPA]

http://arxiv.org/abs/2304.09215


We present a review of Saturn’s interior structure and thermal evolution, with a particular focus on work in the past 5 years. Data from the Cassini mission, including a precise determination of the gravity field from the Grand Finale orbits, and the still ongoing identification of ring wave features in Saturn’s C-ring tied to seismic modes in the planet, have led to dramatic advances in our understanding of Saturn’s structure. Models that match the gravity field suggest that differential rotation, as seen in the visible atmosphere, extends down to at least a depth of 10,000 km (1/6$^{\rm th}$ the planet’s radius). At greater depths, a variety of different investigations all now point to a deep Saturn rotation rate of 10 hours and 33 minutes. There is very compelling evidence for a central heavy element concentration (“core”), that in most recent models is 12-20 Earth masses. Ring seismology strongly suggests that the core is not entirely compact, but is dilute (mixed in with the overlying H/He), and has a substantial radial extent, perhaps out to around one-half of the planet’s radius. A wide range of thermal evolution scenarios can match the planet’s current luminosity, with progress on better quantifying the helium rain scenario hampered by Saturn’s poorly known atmospheric helium abundance. We discuss the relevance of magnetic field data on understanding the planet’s current interior structure. We point towards additional future work that combines seismology and gravity within a framework that includes differential rotation, and the utility of a Saturn entry probe.

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J. Fortney, B. Militzer, C. Mankovich, et. al.
Thu, 20 Apr 23
57/57

Comments: Invited review. Accepted for publication in “Saturn: The Grand Finale”, K. H. Baines et al., eds., Cambridge University Press. All-new follow-up to previous 2016 (pre-Grand Finale) review chapter here: arXiv:1609.06324

Constraints on Europa's water group torus from HST/COS observations [EPA]

http://arxiv.org/abs/2304.09150


In-situ plasma measurements as well as remote mapping of energetic neutral atoms around Jupiter provide indirect evidence that an enhancement of neutral gas is present near the orbit of the moon Europa. Simulations suggest that such a neutral gas torus can be sustained by escape from Europa’s atmosphere and consists primarily of molecular hydrogen, but the neutral gas torus has not yet been measured directly through emissions or in-situ. Here we present observations by the Cosmic Origins Spectrograph of the Hubble Space Telescope (HST/COS) from 2020 and 2021, which scanned the equatorial plane between 8 and 10 planetary radii west of Jupiter. No neutral gas emissions are detected. We derive upper limits on the emissions and compare these to modelled emissions from electron impact and resonant scattering using a Europa torus Monte Carlo model for the neutral gases. The comparison supports the previous findings that the torus is dilute and primarily consists of molecular hydrogen. A detection of sulfur ion emissions radially inward of the Europa orbit is consistent with emissions from the extended Io torus and with sulfur ion fractional abundances as previously detected.

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L. Roth, H. Smith, K. Yoshioka, et. al.
Wed, 19 Apr 23
2/58

Comments: N/A

Mapping the Skies of Ultracool Worlds: Detecting Storms and Spots with Extremely Large Telescopes [EPA]

http://arxiv.org/abs/2304.08518


Extremely large telescopes (ELTs) present an unparalleled opportunity to study the magnetism, atmospheric dynamics, and chemistry of very low mass stars (VLMs), brown dwarfs, and exoplanets. Instruments such as the Giant Magellan Telescope – Consortium Large Earth Finder (GMT/GCLEF), the Thirty Meter Telescope’s Multi-Objective Diffraction-limited High-Resolution Infrared Spectrograph (TMT/MODHIS), and the European Southern Observatory’s Mid-Infrared ELT Imager and Spectrograph (ELT/METIS) provide the spectral resolution and signal-to-noise (S/N) necessary to Doppler image ultracool targets’ surfaces based on temporal spectral variations due to surface inhomogeneities. Using our publicly-available code, $Imber$, developed and validated in Plummer & Wang (2022), we evaluate these instruments’ abilities to discern magnetic star spots and cloud systems on a VLM star (TRAPPIST-1); two L/T transition ultracool dwarfs (VHS J1256$-$1257 b and SIMP J0136+0933); and three exoplanets (Beta Pic b and HR 8799 d and e). We find that TMT/MODHIS and ELT/METIS are suitable for Doppler imaging the ultracool dwarfs and Beta Pic b over a single rotation. Uncertainties for longitude and radius are typically $\lesssim 10^{\circ}$, and latitude uncertainties range from $\sim 10^{\circ} \ \rm{to} \ 30^{\circ}$. TRAPPIST-1’s edge-on inclination and low $\upsilon \sin i$ provide a challenge for all three instruments while GMT/GCLEF and the HR 8799 planets may require observations over multiple rotations. We compare the spectroscopic technique, photometry-only inference, and the combination of the two. We find combining spectroscopic and photometric observations can lead to improved Bayesian inference of surface inhomogeneities and offers insight into whether ultracool atmospheres are dominated by spotted or banded features.

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M. Plummer and J. Wang
Wed, 19 Apr 23
11/58

Comments: Accepted for publication in The Astrophysical Journal, 26 pages, 10 figures, 3 tables

Radiometry for Nighttime Sub-Cloud Imaging of Venus' Surface in the Near-InfraRed Spectrum [EPA]

http://arxiv.org/abs/2304.08585


Does radiometry (e.g., signal-to-noise ratio) limit the performance of near-IR subcloud imaging of our sister planet’s surface at night? It does not. We compute subcloud radiometry using above-cloud observations, an assumed ground temperature, sub-cloud absorption and emission modeling, and Rayleigh scattering simulations. We thus confirm both archival and recent studies that deployment of a modest subcloud camera does enable high-resolution surface imaging.

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B. Sutin, A. Davis, K. Baines, et. al.
Wed, 19 Apr 23
34/58

Comments: 14 pages, 8 figures

Surface pressure impact on nitrogen-dominated USP super-Earth atmospheres [EPA]

http://arxiv.org/abs/2304.08690


In this paper, we compare the chemistry and the emission spectra of nitrogen-dominated cool, warm, and hot ultra-short-period (USP) super-Earth atmospheres in and out of chemical equilibrium at various surface pressure scenarios ranging from 0.1 to 10 bar. We link the one-dimensional VULCAN chemical kinetic code, in which thermochemical kinetic and vertical transport and photochemistry are taken into account, to the one-dimensional radiative transfer model, PETITRADTRANS, to predict the emission spectra of these planets. The radiative-convective temperature-pressure profiles were computed with the HELIOS code. Then, using PANDEXO noise simulator, we explore the observability of the differences produced by disequilibrium processes with the JWST. Our grids show how different surface pressures can significantly affect the temperature profiles, the atmospheric abundances, and consequently the emission spectra of these planets. We find that the divergences due to disequilibrium processes would be possible to observe in cooler planets by targeting HCN, C2H4, and CO, and in warmer planets by targeting CH4 with HCN, using the NIRSpec and MIRI LRS JWST instruments. These species are also found to be sensitive indicators of the existence of surfaces on nitrogen-dominated USP super-Earths, providing information regarding the thickness of these atmospheres.

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J. Chouqar, J. Lustig-Yaeger, Z. Benkhaldoun, et. al.
Wed, 19 Apr 23
38/58

Comments: 12 pages

Secular orbital dynamics of the innermost exoplanet of the $\upsilon$-Andromedæ system [EPA]

http://arxiv.org/abs/2304.09038


We introduce a quasi-periodic restricted Hamiltonian to describe the secular motion of a small-mass planet in a multi-planetary system. In particular, we refer to the motion of $\upsilon$-And $b$ which is the innermost planet among those discovered in the extrasolar system orbiting around the $\upsilon$-Andromedae A star. We preassign the orbits of the Super-Jupiter exoplanets $\upsilon$-And $c$ and $\upsilon$-And $d$ in a stable configuration. The Fourier decompositions of their secular motions are reconstructed by using the Frequency Analysis and are injected in the equations describing the orbital dynamics of $\upsilon$-And $b$ under the gravitational effects exerted by those two external exoplanets (expected to be major ones in such an extrasolar system). We end up with a $2+3/2$ degrees of freedom Hamiltonian model; its validity is confirmed by the comparison with several numerical integrations of the complete $4$-body problem. Furthermore, the model is enriched by taking into account also the relativistic effects on the secular motion of the innermost exoplanet. We focus on the problem of the stability of $\upsilon$-And $b$ as a function of the parameters that mostly impact on its orbit, i.e. the initial values of its inclination and the longitude of its node. We study the evolution of its eccentricity, crucial to exclude orbital configurations with high probability of (quasi)collision with the central star in the long-time evolution of the system. Moreover, we also introduce a normal form approach, that further reduces our Hamiltonian model to a system with $2$ degrees of freedom, which is integrable because it admits a constant of motion related to the total angular momentum. This allows us to quickly preselect the domains of stability for $\upsilon$-And $b$, with respect to the set of the initial orbital configurations that are compatible with the observations.

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R. Mastroianni and U. Locatelli
Wed, 19 Apr 23
48/58

Comments: N/A

MHD study of extreme space weather conditions for exoplanets with Earth-like magnetospheres: On habitability conditions and radio-emission [EPA]

http://arxiv.org/abs/2304.08771


The present study aims at characterizing the habitability conditions of exoplanets with an Earth-like magnetosphere inside the habitable zone of M stars and F stars like tau Boo, caused by the direct deposition of the stellar wind on the exoplanet surface if the magnetosphere shielding is inefficient. In addition, the radio emission generated by exoplanets with a Earth-like magnetosphere is calculated for different space weather conditions. The study is based on a set of MHD simulations performed by the code PLUTO reproducing the space weather conditions expected for exoplanets orbiting the habitable zone of M stars and F stars type tau Boo. Exoplanets hosted by M stars at 0.2 au are protected from the stellar wind during regular and CME-like space weather conditions if the star rotation period is slower than 3 days, that is to say, faster rotators generate stellar winds and interplanetary magnetic fields large enough to endanger the exoplanet habitability. Exoplanets hosted by a F stars type tau Boo at >= 2.5 au are protected during regular space weather conditions, but a stronger magnetic field compared to the Earth is mandatory if the exoplanet is close to the inner edge of the star habitable zone (2.5 au) to shield the exoplanet surface during CME-like space weather conditions. The range of radio emission values calculated in the simulations are consistent with the scaling proposed by [Zarka 2018] during regular and common CME-like space weather conditions. If the radio telescopes measure a relative low radio emission signal with small variability from an exoplanet, that may indicate favorable exoplanet habitability conditions with respect to the space weather states considered and the intrinsic magnetic field of the exoplanet.

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J. Varela, A. Brun, P. Zarka, et. al.
Wed, 19 Apr 23
49/58

Comments: N/A

Geoeffectiveness of Interplanetary Shocks Controlled by Impact Angles: Past Research, Recent Advancements, and Future Work [CL]

http://arxiv.org/abs/2304.08254


Interplanetary (IP) shocks are disturbances commonly observed in the solar wind. IP shock impacts can cause a myriad of space weather effects in the Earth’s magnetopause, inner magnetosphere, ionosphere, thermosphere, and ground magnetic field. The shock impact angle, measured as the angle the shock normal vector performs with the Sun-Earth line, has been shown to be a very important parameter that controls shock geoeffectivess. An extensive review provided by Oliveira and Samsonov (2018) summarized all the work known at the time with respect to shock impact angles and geomagnetic activity; however, this topic has had some progress since Oliveira and Samsonov (2018) and the main goal of this mini review is to summarize all achievements to date in the topic to the knowledge of the author. Finally, this mini review also brings a few suggestions and ideas for future research in the area of IP shock impact angle geoeffectiveness.

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D. Oliveira
Tue, 18 Apr 23
2/80

Comments: 13 pages, 1 figuew

Residual eccentricity of an Earth-like planet orbiting a red giant Sun [EPA]

http://arxiv.org/abs/2304.07808


The late phases of the orbital evolution of an Earth-like planet around a Sun-like star are revisited considering the effect of the density fluctuations associated with convective motions inside the star. Such fluctuations produce a random perturbation of the stellar outer gravitational field that excites a small residual eccentricity in the orbit of the planet counteracting the effects of tides that tend to circularize the orbit. We compute the power spectrum of the outer gravitational field fluctuations of the star in the quadrupole approximation and study their effects on the orbit of the planet using a perturbative approach. The residual eccentricity is found to be a stochastic variable showing a Gaussian distribution. Adopting a model of the stellar evolution of our Sun computed with MESA, we find that the Earth will be engulfed close to the tip of the red giant branch evolution phase. We find a maximum mean value of the residual eccentricity of about 0.026 immediately before the engulfment. Considering an Earth-mass planet with an initial orbital semimajor axis sufficiently large to escape engulfment, we find that the mean value of the residual eccentricity is greater than 0.01 for an initial separation up to about 1.4 au. The engulfment of the Earth by the red giant Sun is found to be a stochastic process, in contrast to the deterministic character assumed in previous studies. If an Earth-like planet escapes engulfment, its orbit around its remnant white dwarf star will be moderately eccentric. Such a residual eccentricity on the order of a few hundredths can play a relevant role in sustaining the pollution of the white dwarf atmosphere by asteroids and comets as observed in several objects.

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A. Lanza, Y. Lebreton and C. Sallard
Tue, 18 Apr 23
15/80

Comments: 18 pages, 6 figures, 3 appendixes, accepted by Astronomy & Astrophysics

A hydrodynamic study of the escape of metal species and excited hydrogen from the atmosphere of the hot Jupiter WASP-121b [EPA]

http://arxiv.org/abs/2304.07352


In the near-UV and optical transmission spectrum of the hot Jupiter WASP-121b, recent observations have detected strong absorption features of Mg, Fe, Ca, and H$\alpha$, extending outside of the planet’s Roche lobe. Studying these atomic signatures can directly trace the escaping atmosphere and constrain the energy balance of the upper atmosphere. To understand these features, we introduce a detailed forward model by expanding the capability of a one-dimensional model of the upper atmosphere and hydrodynamic escape to include important processes of atomic metal species. The hydrodynamic model is coupled to a Ly$\alpha$ Monte Carlo radiative transfer calculation to simulate the excited hydrogen population and associated heating/ionization effects. Using this model, we interpret the detected atomic features in the transmission spectrum of WASP-121b and explore the impact of metals and excited hydrogen on its upper atmosphere. We demonstrate the use of multiple absorption lines to impose stronger constraints on the properties of the upper atmosphere than the analysis of a single transmission feature can provide. In addition, the model shows that line broadening due to atmospheric outflow driven by the Roche lobe overflow is necessary to explain the observed line widths and highlights the importance of the high mass-loss rate caused by the Roche lobe overflow that requires careful consideration of the structure of the lower and middle atmosphere. We also show that metal species and excited state hydrogen can play an important role in the thermal and ionization balance of ultra-hot Jupiter thermospheres.

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C. Huang, T. Koskinen, P. Lavvas, et. al.
Tue, 18 Apr 23
22/80

Comments: 35 pages, 31 figures, Accepted for publication in ApJ

Parallelization of the Symplectic Massive Body Algorithm (SyMBA) $N$-body Code [EPA]

http://arxiv.org/abs/2304.07325


Direct $N$-body simulations of a large number of particles, especially in the study of planetesimal dynamics and planet formation, have been computationally challenging even with modern machines. This work presents the combination of fully parallelized $N^2/2$ interactions and the incorporation of the GENGA code’s close encounter pair grouping strategy to enable MIMD parallelization of the Symplectic Massive Body Algorithm (SyMBA) with OpenMP on multi-core CPUs in shared-memory environment. SyMBAp (SyMBA parallelized) preserves the symplectic nature of SyMBA and shows good scalability, with a speedup of 30.8 times with 56 cores in a simulation with 5,000 fully interactive particles.

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T. Lau and M. Lee
Tue, 18 Apr 23
23/80

Comments: Accepted for publication in Research Notes of the AAS

Three-dimensional magnetic field imaging of protoplanetary disks using Zeeman broadening and linear polarization observations [EPA]

http://arxiv.org/abs/2304.07346


Magnetic fields are predicted to have a crucial impact on the structure, evolution and chemistry of protoplanetary disks. However, a direct detection of the magnetic field towards these objects has yet to be achieved. In order to characterize protoplanetary disk magnetic fields, we investigate the impact of the Zeeman effect on the (polarized) radiative transfer of emission from paramagnetic molecules excited in protoplanetary disks. While the effects of the Zeeman effect are commonly studied in the circular polarization of spectral lines, we perform a comprehensive modeling also of the Zeeman-induced broadening of spectral lines and their linear polarization. We develop simplified radiative transfer models adapted to protoplanetary disks, which we compare to full three-dimensional polarized radiative transfer simulations. We find that the radiative transfer of circular polarization is heavily affected by the expected polarity-change of the magnetic field between opposite sides of the disk. In contrast, Zeeman broadening and linear polarization are relatively unaffected by this sign change due to their quadratic dependence on the magnetic field. We can match our simplified radiative transfer models to full polarization modeling with high fidelity, which in turn allows us to prescribe straight-forward methods to extract magnetic field information from Zeeman broadening and linear polarization observations. We find that Zeeman broadening and linear polarization observations are highly advantageous methods to characterize protoplanetary disk magnetic fields as they are both sensitive probes of the magnetic field and are marginally affected by any sign change of the disk magnetic field. Applying our results to existing circular polarization observations of protoplanetary disk spectral lines suggests that the current upper limits on the toroidal magnetic field strengths have to be raised.

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B. Lankhaar and R. Teague
Tue, 18 Apr 23
31/80

Comments: 22 pages, 10 figures, accepted to A&A

Earth shaped by primordial H$_2$ atmospheres [EPA]

http://arxiv.org/abs/2304.07845


Earth’s water, intrinsic oxidation state, and metal core density are fundamental chemical features of our planet. Studies of exoplanets provide a useful context for elucidating the source of these chemical traits. Planet formation and evolution models demonstrate that rocky exoplanets commonly formed with hydrogen-rich envelopes that were lost over time. These findings suggest that Earth may also have formed from bodies with H$_2$-rich primary atmospheres. Here we use a self-consistent thermodynamic model to show that Earth’s water, core density, and overall oxidation state can all be sourced to equilibrium between H$_2$-rich primary atmospheres and underlying magma oceans in its progenitor planetary embryos. Water is produced from dry starting materials resembling enstatite chondrites as oxygen from magma oceans reacts with hydrogen. Hydrogen derived from the atmosphere enters the magma ocean and eventually the metal core at equilibrium, causing metal density deficits matching that of Earth. Oxidation of the silicate rocks from solar-like to Earth-like oxygen fugacities also ensues as Si, along with H and O, alloys with Fe in the cores. Reaction with hydrogen atmospheres and metal-silicate equilibrium thus provides a simple explanation for fundamental features of Earth’s geochemistry that is consistent with rocky planet formation across the galaxy.

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E. Young, A. Shahar and H. Schlichting
Tue, 18 Apr 23
32/80

Comments: 3 main figures, 5 auxiliary figures

Observing atmospheric escape in sub-Jovian worlds with JWST [EPA]

http://arxiv.org/abs/2304.07792


Hydrodynamic atmospheric escape is considered an important process that shapes the evolution of sub-Jovian exoplanets, particularly those with short orbital periods. The metastable He line in the near-infrared at $1.083$ $\mu$m is a reliable tracer of atmospheric escape in hot exoplanets, with the advantage of being observable from the ground. However, observing escaping He in sub-Jovian planets has remained challenging due to the systematic effects and telluric contamination present in ground-based data. With the successful launch and operations of JWST, we now have access to extremely stable high-precision near-infrared spectrographs in space. Here we predict the observability of metastable He with JWST in two representative and previously well-studied warm Neptunes, GJ 436 b ($T_{\rm eq} = 687~{\rm K}$, $R_{\rm p} = 0.37~{\rm R_J}$) and GJ 1214 b ($T_{\rm eq} = 588~{\rm K}$, $R_{\rm p} = 0.25~{\rm R_J}$). Our simulated JWST observations for GJ 436 b demonstrate that a single transit with NIRSpec/G140H is sensitive to mass loss rates that are two orders of magnitude lower than what is detectable from the ground. Our exercise for GJ 1214 b show that the best configuration to observe the relatively weak outflows of warm Neptunes with JWST is with NIRSpec/G140H, and that NIRSpec/G140M and NIRISS/SOSS are less optimal. Since none of these instrument configurations can spectrally resolve the planetary absorption, we conclude that the 1D isothermal Parker-wind approximation may not be sufficient for interpreting such observations. More sophisticated models are critical for breaking the degeneracy between outflow temperature and mass-loss rate for JWST measurements of metastable He.

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L. Santos, M. Alam, N. Espinoza, et. al.
Tue, 18 Apr 23
39/80

Comments: 14 pages, 7 figures, under review at AAS Journals; this version follows the first round of revision. Feedback from the community is welcome

A high spatial and spectral resolution study of Jupiter's mid-infrared auroral emissions and their response to a solar wind compression [EPA]

http://arxiv.org/abs/2304.08390


We present mid-infrared spectroscopy of Jupiter’s mid-to-high latitudes using Gemini-North/TEXES (Texas Echelon Cross Echelle Spectrograph) on March 17-19, 2017. These observations capture Jupiter’s hydrocarbon auroral emissions before, during and after the arrival of a solar wind compression on March 18th, which highlights the coupling between the polar stratosphere and external space environment. In comparing observations on March 17th and 19th, we observe a brightening of the CH$_4$, C$_2$H$_2$ and C$_2$H$_4$ emissions in regions spatially coincident with the northern, duskside main auroral emission (henceforth, MAE). In inverting the spectra to derive atmospheric information, we determine that the duskside brightening results from an upper stratospheric (p < 0.1 mbar/z > 200 km) heating (e.g. $\Delta T$ = 9.1 $\pm$ 2.1 K at 9 $\mu$bar at 67.5$^\circ$N, 162.5$^\circ$W) with negligible heating at deeper pressures. Our interpretation is that the arrival of the solar wind enhancement drove magnetospheric dynamics through compression and/or viscous interactions on the flank. These dynamics accelerated currents and/or generated higher Poynting fluxes, which ultimately warmed the atmosphere through Joule heating and ion-neutral collisions. Poleward of the southern MAE, temperature retrievals demonstrate that auroral-related heating penetrates as deep as the 10-mbar level, in contrast to poleward of the northern MAE, where heating is only observed as deep as $\sim$3 mbar. We suggest this results from the south having higher Pedersen conductivities, and therefore stronger currents and acceleration of the neutrals, as well as the poleward heating overlapping with the apex of Jupiter’s circulation thereby inhibiting efficient horizontal mixing/advection.

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J. Sinclair, T. Greathouse, R. Giles, et. al.
Tue, 18 Apr 23
43/80

Comments: N/A

The apparent absence of forward scattering in the HD 53143 debris disk [EPA]

http://arxiv.org/abs/2304.07370


HD 53143 is a mature Sun-like star and host to a broad disk of dusty debris, including a cold outer ring of planetesimals near 90 AU. Unlike most other inclined debris disks imaged at visible wavelengths, the cold disk around HD 53143 appears as disconnected “arcs” of material, with no forward scattering side detected to date. We present new, deeper Hubble Space Telescope (HST) Space Telescope Imaging Spectrograph (STIS) coronagraphic observations of the HD 53143 debris disk and show that the forward scattering side of the disk remains undetected. By fitting our KLIP-reduced observations via forward modeling with an optically thin disk model, we show that fitting the visible wavelength images with an azimuthally symmetric disk with unconstrained orientation results in an unphysical edge-on orientation that is at odds with recent ALMA observations, while constraining the orientation to that observed by ALMA results in nearly isotropically scattering dust. We show that the HD53143 host star exhibits significant stellar variations due to spot rotation and revisit age estimates for this system.

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C. Stark, B. Ren, M. MacGregor, et. al.
Tue, 18 Apr 23
53/80

Comments: 13 pages, 8 figures, 2 tables Accepted for publication in ApJ

Evidence for Misalignment Between Debris Disks and Their Host Stars [EPA]

http://arxiv.org/abs/2304.07446


We place lower limits on the obliquities between debris disks and their host stars for 31 systems by comparing their disk and stellar inclinations. While previous studies did not find evidence for misalignment, we identify 6 systems with minimum obliquities falling between ~30{\deg}-60{\deg}, indicating that debris disks can be significantly misaligned with their stars. These high-obliquity systems span a wide range of stellar parameters with spectral types K through A. Previous works have argued that stars with masses below 1.2 $M_\odot$ (spectral types of ~F6) have magnetic fields strong enough to realign their rotation axes with the surrounding disk via magnetic warping; given that we observe high obliquities for relatively low-mass stars, magnetic warping alone is likely not responsible for the observed misalignment. Yet, chaotic accretion is expected to result in misalignments of ~20{\deg} at most and cannot explain the larger obliquities found in this work. While it remains unclear how primordial misalignment might occur and what role it plays in determining the spin-orbit alignment of planets, future work expanding this sample is critical towards understanding the mechanisms that shape these high-obliquity systems.

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S. Hurt and M. MacGregor
Tue, 18 Apr 23
57/80

Comments: Accepted to The Astrophysical Journal (ApJ)

Microwave Observations of Venus with CLASS [EPA]

http://arxiv.org/abs/2304.07367


We report on the disk-averaged absolute brightness temperatures of Venus measured at four microwave frequency bands with the Cosmology Large Angular Scale Surveyor (CLASS). We measure temperatures of 432.3 $\pm$ 2.8 K, 355.6 $\pm$ 1.3 K, 317.9 $\pm$ 1.7 K, and 294.7 $\pm$ 1.9 K for frequency bands centered at 38.8, 93.7, 147.9, and 217.5 GHz, respectively. We do not observe any dependence of the measured brightness temperatures on solar illumination for all four frequency bands. A joint analysis of our measurements with lower frequency Very Large Array (VLA) observations suggests relatively warmer ($\sim$ 7 K higher) mean atmospheric temperatures and lower abundances of microwave continuum absorbers than those inferred from prior radio occultation measurements.

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S. Dahal, M. Brewer, A. Akins, et. al.
Tue, 18 Apr 23
65/80

Comments: 10 pages, 3 figures, submitted to PSJ

Climatologies of Various OH Lines From About 90,000 X-shooter Spectra [CL]

http://arxiv.org/abs/2304.08206


The nocturnal mesopause region of the Earth’s atmosphere radiates chemiluminescent emission from various roto-vibrational bands of hydroxyl (OH), which is therefore a good tracer of the chemistry and dynamics at the emission altitudes. Intensity variations can, e.g., be caused by the general circulation, gravity waves, tides, planetary waves, and the solar activity. While the basic OH response to the different dynamical influences has been studied quite frequently, detailed comparisons of the various individual lines are still rare. Such studies can improve our understanding of the OH-related variations as each line shows a different emission profile. We have therefore used about 90,000 spectra of the X-shooter spectrograph of the Very Large Telescope at Cerro Paranal in Chile in order to study 10 years of variations of 298 OH lines. The analysis focuses on climatologies of intensity, solar cycle effect, and residual variability (especially with respect to time scales of hours and about 2 days) for day of year and local time. For a better understanding of the resulting variability patterns and the line-specific differences, we applied decomposition techniques, studied the variability depending on time scale, and calculated correlations. As a result, the mixing of thermalized and nonthermalized OH level populations clearly influences the amplitude of the variations. Moreover, the local times of the variability features shift depending on the effective line emission height, which can mainly be explained by the propagation of the migrating diurnal tide. This behavior also contributes to remarkable differences in the effective solar cycle effect.

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S. Noll, C. Schmidt, W. Kausch, et. al.
Tue, 18 Apr 23
70/80

Comments: 35 single-column pages and 12 figures; accepted for publication in J. Geophys. Res. Atmos

GREX-PLUS Science Book [CEA]

http://arxiv.org/abs/2304.08104


GREX-PLUS (Galaxy Reionization EXplorer and PLanetary Universe Spectrometer) is a mission candidate for a JAXA’s strategic L-class mission to be launched in the 2030s. Its primary sciences are two-fold: galaxy formation and evolution and planetary system formation and evolution. The GREX-PLUS spacecraft will carry a 1.2 m primary mirror aperture telescope cooled down to 50 K. The two science instruments will be onboard: a wide-field camera in the 2-8 $\mu$m wavelength band and a high resolution spectrometer with a wavelength resolution of 30,000 in the 10-18 $\mu$m band. The GREX-PLUS wide-field camera aims to detect the first generation of galaxies at redshift $z>15$. The GREX-PLUS high resolution spectrometer aims to identify the location of the water “snow line” in proto-planetary disks. Both instruments will provide unique data sets for a broad range of scientific topics including galaxy mass assembly, origin of supermassive blackholes, infrared background radiation, molecular spectroscopy in the interstellar medium, transit spectroscopy for exoplanet atmosphere, planetary atmosphere in the Solar system, and so on.

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G. Team, A. Inoue, Y. Harikane, et. al.
Tue, 18 Apr 23
77/80

Comments: This document is the first version of a collection of scientific themes which can be achieved with GREX-PLUS. Each section in Chapters 2 and 3 is based on the presentation at the GREX-PLUS Science Workshop held on 24-25 March, 2022 at Waseda University

A statistical model of stellar variability. I. FENRIR: a physics-based model of stellar activity, and its fast Gaussian process approximation [SSA]

http://arxiv.org/abs/2304.08489


The detection of terrestrial planets by radial velocity and photometry is hindered by the presence of stellar signals. Those are often modeled as stationary Gaussian processes, whose kernels are based on qualitative considerations, which do not fully leverage the existing physical understanding of stars. Our aim is to build a formalism which allows to transfer the knowledge of stellar activity into practical data analysis methods. In particular, we aim at obtaining kernels with physical parameters. This has two purposes: better modelling signals of stellar origin to find smaller exoplanets, and extracting information about the star from the statistical properties of the data. We consider several observational channels such as photometry, radial velocity, activity indicators, and build a model called FENRIR to represent their stochastic variations due to stellar surface inhomogeneities. We compute analytically the covariance of this multi-channel stochastic process, and implement it in the S+LEAF framework to reduce the cost of likelihood evaluations from $O(N^3)$ to $O(N)$. We also compute analytically higher order cumulants of our FENRIR model, which quantify its non-Gaussianity. We obtain a fast Gaussian process framework with physical parameters, which we apply to the HARPS-N and SORCE observations of the Sun, and constrain a solar inclination compatible with the viewing geometry. We then discuss the application of our formalism to granulation. We exhibit non-Gaussianity in solar HARPS radial velocities, and argue that information is lost when stellar activity signals are assumed to be Gaussian. We finally discuss the origin of phase shifts between RVs and indicators, and how to build relevant activity indicators. We provide an open-source implementation of the FENRIR Gaussian process model with a Python interface.

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N. Hara and J. Delisle
Tue, 18 Apr 23
79/80

Comments: Submitted to Astronomy \& Astrophysics

Revisiting the trajectory of the interstellar object 'Oumuamua: preference for a radially directed non-gravitational acceleration? [EPA]

http://arxiv.org/abs/2304.06964


I present a re-analysis of the available observational constraints on the trajectory of ‘Oumuamua, the first confirmed interstellar object discovered in the solar system. ‘Oumuamua passed through the inner solar system on a hyperbolic (i.e., unbound) trajectory. Its discovery occurred after perihelion passage, and near the time of its closest approach to Earth. After being observable for approximately four months, the object became too faint and was lost at a heliocentric distance of around 3 au. Intriguingly, analysis of the trajectory of ‘Oumuamua revealed that a dynamical model including only gravitational accelerations does not provide a satisfactory fit of the data, and a non-gravitational term must be included. The detected non-gravitational acceleration is compatible with either solar radiation pressure or recoil due to outgassing. It has, however, proved challenging to reconcile either interpretation with the existing quantitative models of such effects without postulating unusual physical properties for ‘Oumuamua (such as extremely low density and/or unusual geometry, non-standard chemistry). My analysis independently confirms the detection of the non-gravitational acceleration. After comparing several possible parametrizations for this effects, I find a strong preference for a radially directed non-gravitational acceleration, pointing away from the Sun, and a moderate preference for a power-law scaling with the heliocentric distance, with an exponent between 1 and 2. These results provide valuable constraints on the physical mechanism behind the effect; a conclusive identification, however, is probably not possible on the basis of dynamical arguments alone.

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F. Spada
Mon, 17 Apr 23
16/51

Comments: MATLAB code will be shared upon reasonable request to the author. Comments are welcome!

Magnetic winding and turbulence in ultra-hot Jupiters [EPA]

http://arxiv.org/abs/2304.07066


While magnetism in exoplanets remains largely unknown, Hot Jupiters have been considered as natural candidates to harbour intense magnetic fields, both due to their large masses and their high energy budgets coming from irradiation as a consequence of their vicinity to their host stars. In this work we perform MHD simulations of a narrow day-side atmospheric column of ultra-hot Jupiters, suitable for very high local temperatures (T > 3000 K). Since the conductivity in this regime is very high, the dominant effect is winding due to the intense zonal winds. By including a forcing that mimics the wind profiles obtained in global circulation models, the shear layer induces a strong toroidal magnetic field (locally reaching hundreds of gauss), supported by meridional currents. Such fields and the sustaining currents don$’$t depend on the internally generated field, but are all confined in the thin (less than a scale-height) shear layer around 1 bar. Additionally, we add random perturbations that induce turbulent motions, which lead to further (but much smaller) magnetic field generation to a broader range of depths. These results allow an evaluation of the currents induced by the atmospheric dynamo. Although here we use ideal MHD and the only resistivity comes from the numerical scheme, we estimate a-posteriori the amount of Ohmic heat deposited in the outer layers, which could be employed in evolutionary models for Hot Jupiters’ inflated radii.

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C. Soriano-Guerrero, D. Viganò, R. Perna, et. al.
Mon, 17 Apr 23
38/51

Comments: submitted for publication in MNRAS

Planet Eclipse Mapping with Long-Term Baseline Drifts [EPA]

http://arxiv.org/abs/2304.06851


High precision lightcurves combined with eclipse mapping techniques can reveal the horizontal and vertical structure of a planet’s thermal emission and the dynamics of hot Jupiters. Someday, they even may reveal the surface maps of rocky planets. However, inverting lightcurves into maps requires an understanding of the planet, star and instrumental trends because they can resemble the gradual flux variations as the planet rotates (ie. partial phase curves). In this work, we simulate lightcurves with baseline trends and assess the impact on planet maps. Baseline trends can be erroneously modeled by incorrect astrophysical planet map features, but there are clues to avoid this pitfall in both the residuals of the lightcurve during eclipse and sharp features at the terminator of the planet. Models that use a Gaussian process or polynomial to account for a baseline trend successfully recover the input map even in the presence of systematics but with worse precision for the m=1 spherical harmonic terms. This is also confirmed with the ThERESA eigencurve method where fewer lightcurve terms can model the planet without correlations between the components. These conclusions help aid the decision on how to schedule observations to improve map precision. If the m=1 components are critical, such as measuring the East/West hotspot shift on a hot Jupiter, better characterization of baseline trends can improve the m=1 terms’ precision. For latitudinal North/South information from the remaining mapping terms, it is preferable to obtain high signal-to-noise at ingress/egress with more eclipses.

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E. Schlawin, R. Challener, M. Mansfield, et. al.
Mon, 17 Apr 23
51/51

Comments: AJ, accepted, 22 pages

A physically derived eddy parameterization for giant planet atmospheres with application on hot-Jupiter atmospheres [EPA]

http://arxiv.org/abs/2304.06314


We present a parameterization for the eddy diffusion profile of gas giant exoplanets based on physical phenomena and we explore how the parameterized eddy profile impacts the chemical composition, the thermal structure, the haze microphysics, and the transit spectra of 8 hot-Jupiters. Our eddy parameterization depends on the planetary intrinsic temperature (T${int}$ ), we thus evaluate how the increase of this parameter to values higher than those typically used ($\sim$100K) impacts the atmospheric structure and composition. Our investigation demonstrates that despite the strong impact of T${int}$ on the chemical composition of the deep atmosphere, the upper atmosphere is not affected for T${eq}$ $>$ 1300 K owing to high altitude quench levels at these conditions. Below this threshold, however, the larger atmospheric temperatures produced by increasing T${int}$ affect the quenched chemical composition. Our parameterization depends on two parameters, the eddy magnitude at the radiative-convective boundary (K$0$) and the corresponding magnitude at the homopause (K${top}$). We demonstrate that, when using common K$0$ and K${top}$ values among most of the different planet cases studied, we derive transit spectra consistent with Hubble Space Telescope observations. Moreover, our simulations show that increasing the eddy profile enhances the photochemical production of haze particles and reduces their average radius, thus providing a steeper UV-Visible slope. Finally, we demonstrate for WASP-39b that the James Webb Space Telescope observations provide improved constraints for the hazes and clouds and we show that both components seem necessary to interpret the combined transit spectrum from HST and JWST observations.

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A. Arfaux and P. Lavvas
Fri, 14 Apr 23
10/64

Comments: 19 pages, 12 figures

TOI-733 b — a planet in the small-planet radius valley orbiting a Sun-like star [EPA]

http://arxiv.org/abs/2304.06655


We report the discovery of a hot ($T_{\rm eq}$ $\approx$ 1055 K) planet in the small planet radius valley transiting the Sun-like star TOI-733, as part of the KESPRINT follow-up program of TESS planets carried out with the HARPS spectrograph. TESS photometry from sectors 9 and 36 yields an orbital period of $P_{\rm orb}$ = $4.884765 { – 2.4e-5 } ^ { + 1.9e-5 }$ days and a radius of $R{\mathrm{p}}$ = $1.992 { – 0.090 } ^ { + 0.085 }$ $R{\oplus}$. Multi-dimensional Gaussian process modelling of the radial velocity measurements from HARPS and activity indicators, gives a semi-amplitude of $K$ = $2.23 \pm 0.26 $ m s$^{-1}$, translating into a planet mass of $M_{\mathrm{p}}$ = $5.72 { – 0.68 } ^ { + 0.70 }$ $M{\oplus}$. These parameters imply that the planet is of moderate density ($\rho_\mathrm{p}$ = $3.98 _{ – 0.66 } ^ { + 0.77 }$ g cm$^{-3}$) and place it in the transition region between rocky and volatile-rich planets with H/He-dominated envelopes on the mass-radius diagram. Combining these with stellar parameters and abundances, we calculate planet interior and atmosphere models, which in turn suggest that TOI-733 b has a volatile-enriched, most likely secondary outer envelope, and may represent a highly irradiated ocean world – one of only a few such planets around G-type stars that are well-characterised.

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I. Georgieva, C. Persson, E. Goffo, et. al.
Fri, 14 Apr 23
15/64

Comments: Accepted for publication in A&A

Revisiting K2-233 spectroscopic time-series with multidimensional Gaussian Processes [EPA]

http://arxiv.org/abs/2304.06406


Detecting planetary signatures in radial velocity time-series of young stars is challenging due to their inherently strong stellar activity. However, it is possible to learn information about the properties of the stellar signal by using activity indicators measured from the same stellar spectra used to extract radial velocities. In this manuscript, we present a reanalysis of spectroscopic HARPS data of the young star K2-233, which hosts three transiting planets. We perform a multidimensional Gaussian Process regression on the radial velocity and the activity indicators to characterise the planetary Doppler signals. We demonstrate, for the first time on a real dataset, that the use of a multidimensional Gaussian Process can boost the precision with which we measure the planetary signals compared to a one-dimensional Gaussian Process applied to the radial velocities alone. We measure the semi-amplitudes of K2-233 b, c, and d as 1.31(-0.74)(+0.81), 1.81(-0.67)(+0.71), and 2.72(-0.70)(+0.66) m/s, which translates into planetary masses of 2.4(-1.3)(+1.5), 4.6(-1.7)(+1.8), and 10.3(-2.6)(+2.4), respectively. These new mass measurements make K2-233 d a valuable target for transmission spectroscopy observations with JWST. K2-233 is the only young system with two detected inner planets below the radius valley and a third outer planet above it. This makes it an excellent target to perform comparative studies, to inform our theories of planet evolution, formation, migration, and atmospheric evolution.

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O. Barragán, E. Gillen, S. Aigrain, et. al.
Fri, 14 Apr 23
45/64

Comments: Accepted for publication in MNRAS

Apocenter pile-up and arcs: a narrow dust ring around HD 129590 [EPA]

http://arxiv.org/abs/2304.06074


Observations of debris disks have significantly improved over the past decades, both in terms of sensitivity and spatial resolution. At near-infrared wavelengths, new observing strategies and post-processing algorithms allow us to drastically improve the final images, revealing faint structures in the disks. These structures inform us about the properties and spatial distribution of the small dust particles. We present new $H$-band observations of the disk around HD 129590, which display an intriguing arc-like structure in total intensity but not in polarimetry, and propose an explanation for the origin of this arc. Assuming geometric parameters for the birth ring of planetesimals, our model provides the positions of millions of particles of different sizes to compute scattered light images. We demonstrate that if the grain size distribution is truncated or strongly peaks at a size larger than the radiation pressure blow-out size we are able to produce an arc quite similar to the observed one. If the birth ring is radially narrow, given that particles of a given size have similar eccentricities, they will have their apocenters at the same distance from the star. Since this is where the particles will spend most of their time, this results in a “apocenter pile-up” that can look like a ring. Due to more efficient forward scattering this arc only appears in total intensity observations and remains undetected in polarimetric data. This scenario requires sharp variations either in the grain size distribution or for the scattering efficiencies $Q_\mathrm{sca}$. Alternative possibilities such as a wavy size distribution and a size-dependent phase function are interesting candidates to strengthen the apocenter pile-up. We also discuss why such arcs are not commonly detected in other systems, which can mainly be explained by the fact that most parent belts are usually broad.

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J. Olofsson, P. Thébault, A. Bayo, et. al.
Fri, 14 Apr 23
47/64

Comments: Accepted for publication in A&A, abstract shortened

Investigating the asymmetric chemistry in the disk around the young star HD 142527 [EPA]

http://arxiv.org/abs/2304.06382


The atmospheric composition of planets is determined by the chemistry of the disks in which they form. Studying the gas-phase molecular composition of disks thus allows us to infer what the atmospheric composition of forming planets might be. Recent observations of the IRS 48 disk have shown that (asymmetric) dust traps can directly impact the observable chemistry, through radial and vertical transport, and the sublimation of ices. The asymmetric HD 142527 disk provides another good opportunity to investigate the role of dust traps in setting the disk’s chemical composition. In this work, we use archival ALMA observations of the HD 142527 disk to obtain an as large as possible molecular inventory, which allows us to investigate the possible influence of the asymmetric dust trap on the disk’s chemistry. We present the first ALMA detections of [C I], 13C18O, DCO+, H2CO and additional transition of HCO+ and CS in this disk. In addition, we have acquired upper limits for non-detected species such as SO and CH3OH. For the majority of the observed molecules, a decrement in the emission at the location of the dust trap is found. For the main CO isotopologues continuum over-subtraction likely causes the observed asymmetry, while for CS and HCN we propose that the observed asymmetries are likely due to shadows cast by the misaligned inner disk. As the emission of the observed molecules is not co-spatial with the dust trap and no SO or CH3OH are found, thermal sublimation of icy mantles does not appear to play a major role in changing the gas-phase composition of the outer disk in HD 142527 disk. Using our observations of 13C18O and DCO+ and a RADMC-3D model, we determine the CO snowline to be located beyond the dust traps, favouring cold gas-phase formation of H2CO, rather than the hydrogenation of CO-ice and subsequent sublimation.

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M. Temmink, A. Booth, N. Marel, et. al.
Fri, 14 Apr 23
58/64

Comments: Accepted for publication in A&A on 12/04/2023

Thermal Models of Asteroids with Two-band Combinations of Wide-field Infrared Survey Explorer Cryogenic Data [EPA]

http://arxiv.org/abs/2304.06085


We used the reparameterized Near-Earth Asteroid Thermal Model to model observations of a curated set of over 4000 asteroids from the Wide-field Infrared Survey Explorer in two wavelength bands (W2-3 or W3-4) and compared the results to previous results from all four wavelength bands (W1-4). This comparison was done with the goal of elucidating unique aspects of modeling two-band observations so that any potential biases or shortcomings for planned two-band surveys (e.g., the NASA Near-Earth Object Surveyor Mission) can be anticipated and quantified. The W2-3 two-band fits usually yielded slightly smaller diameters than the four-band fits, with a median diameter difference of -10%, with the 5% and 95% quantiles of the distribution at -32% and -1.5%, respectively. We conducted similar comparisons for W3-4, in part because the longest wavelength bands are expected to provide the best two-band results. We found that the W3-4 two-band diameters are slightly larger than the four-band results, with a median diameter difference of 11% and the 5% and 95% quantiles of the distribution at -2.1% and 26%, respectively. The diameter uncertainty, obtained with bootstrap analysis, is larger by 30% and 35% (median values) for the W2-3 and W3-4 fits, respectively, than for the corresponding four-band fits. Using 23 high-quality stellar occultation diameters as a benchmark, we found that the median errors of W2-3 and W3-4 diameter estimates are -15% and +12%, respectively, whereas the median error of the four-band fits is 9.3%. Although the W2-3 and W3-4 diameters appear to have greater systematic errors and uncertainties than their four-band counterparts, two-band estimates remain useful because they improve upon diameter estimates obtained from visible photometry alone.

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E. Whittaker, J. Margot, A. Lam, et. al.
Fri, 14 Apr 23
64/64

Comments: 18 pages, 21 figures

Dynamics of space debris removal: A review [IMA]

http://arxiv.org/abs/2304.05709


Space debris, also known as “space junk,” presents a significant challenge for all space exploration activities, including those involving human-onboard spacecraft such as SpaceX’s Crew Dragon and the International Space Station. The amount of debris in space is rapidly increasing and poses a significant environmental concern. Various studies and research have been conducted on space debris capture mechanisms, including contact and contact-less capturing methods, in Earth’s orbits. While advancements in technology, such as telecommunications, weather forecasting, high-speed internet, and GPS, have benefited society, their improper and unplanned usage has led to the creation of debris. The growing amount of debris poses a threat of collision with the International Space Station, shuttle, and high-value satellites, and is present in different parts of Earth’s orbit, varying in size, shape, speed, and mass. As a result, capturing and removing space debris is a challenging task. This review article provides an overview of space debris statistics and specifications, and focuses on ongoing mitigation strategies, preventive measures, and statutory guidelines for removing and preventing debris creation, emphasizing the serious issue of space debris damage to space agencies and relevant companies.

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M. Bigdeli, R. Srivastava and M. Scaraggi
Thu, 13 Apr 23
4/59

Comments: N/A

Converting the sub-Jovian desert of exoplanets to a savanna with TESS, PLATO and Ariel [EPA]

http://arxiv.org/abs/2304.05707


There is a lack of exoplanets with sizes similar to Neptune orbiting their host stars with periods $\lesssim 3$ days — hence the name sub-Jovian/Neptune desert''. Recently, several exoplanets have been confirmed to reside in the desert transforming it into asavanna” with several giraffe'' planets (such as LTT 9779 b and TOI-674 b). The most prominent scenarios put forward for the explanation of the formation of the desert are related to the stellar irradiation destroying the primary atmosphere of certain specific exoplanets. We aim to present three targets (LTT 9779 b, TOI-674 b and WASP-156 b) which, when observed at wide wavelength ranges in infrared (IR), could prove the presence of these processes, and therefore improve the theories of planetary formation/evolution. We simulate and analyse realistic light curves of the selected exoplanets with PLATO/NCAM and the three narrow-band filters of Ariel (VISPhot, FGS1 and FGS2) based on TESS observations of these targets. We improved the precision of the transit parameters of the three considered planets from the TESS data. We find that the combination of the three narrow-band filters of Ariel can yield inner precision of $\lesssim 1.1\%$ for the planetary radii. Data from the three telescopes together will span decades, allowing the monitoring of changes in the planetary atmosphere through radius measurements. The three selectedgiraffe” planets can be golden targets for Ariel, whereby the loss of planetary mass due to stellar irradiation could be studied with high precision, multi-wavelength (spectro-)photometry.

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S. Kálmán, G. Szabó, L. Borsato, et. al.
Thu, 13 Apr 23
7/59

Comments: Accepted for publication in MNRAS; 16 pages, 17 figures

Cold Jupiters and improved masses in 38 Kepler and K2 small-planet systems from 3661 high-precision HARPS-N radial velocities. No excess of cold Jupiters in small-planet systems [EPA]

http://arxiv.org/abs/2304.05773


The exoplanet population with orbital periods $P<100$ d around solar-type stars is dominated by super-Earths and sub-Neptunes. These planets are, however, missing in our Solar System, and the reason for that is unknown. Two theoretical scenarios invoke the role of Jupiter as the possible culprit: Jupiter may have acted as a dynamical barrier to the inward migration of sub-Neptunes from beyond the water iceline or, alternatively, may have reduced considerably the inward flux of material (pebbles) required to form super-Earths inside that iceline. Both scenarios predict an anti-correlation between the presence of small planets (SPs) and that of cold Jupiters (CJs) in exoplanetary systems. To test that prediction, we homogeneously analyzed the radial-velocity (RV) measurements of 38 Kepler and K2 transiting SP systems gathered over almost 10 years with the HARPS-N spectrograph, as well as publicly available RVs collected with other facilities. We detected five CJs in three systems, two in Kepler-68, two in Kepler-454, and a very eccentric one in K2-312. We derived an occurrence rate of $9.3^{+7.7}{-2.9}\%$ for CJs with $0.3-13~M{Jup}$ and 1-10 au, which is lower but still compatible at $1.3\sigma$ with that measured from RV surveys for solar-type stars, regardless of SP presence. This does not allow us to draw a firm conclusion about the predicted anti-correlation between SPs and CJs, which would require a considerably larger sample. Nevertheless, we found no evidence of previous claims of an excess of CJs in SP systems. As an important by-product of our analyses, we homogeneously determined the masses of 64 Kepler and K2 small planets, reaching a precision better than 5, 7.5 and 10$\sigma$ for 25, 13 and 8 planets, respectively. Finally, we release to the scientific community the 3661 HARPS-N radial velocities used in this work. [Abridged]

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A. Bonomo, X. Dumusque, A. Massa, et. al.
Thu, 13 Apr 23
8/59

Comments: 21 pages, 10 figures, 10 tables, accepted for publication in Astronomy and Astrophysics on 6 April 2023

Statistical Analysis of Interplanetary Shocks from Mercury to Jupiter [SSA]

http://arxiv.org/abs/2304.05733


In situ observations of interplanetary (IP) coronal mass ejections (ICMEs) and IP shocks are important to study as they are the main components of the solar activity. Hundreds of IP shocks have been detected by various space missions at different times and heliocentric distances. Some of these are followed by clearly identified drivers, while some others are not. In this study, we carry out a statistical analysis of the distributions of plasma and magnetic parameters of the IP shocks recorded at various distances to the Sun. We classify the shocks according to the heliocentric distance, namely from 0.29 to 0.99 AU (Helios-1/2); near 1 AU (Wind, ACE and STEREO-A/B); and from 1.35 to 5.4 AU (Ulysses). We also differentiate the IP shocks into two populations, those with a detected ICME and those without one. We find, as expected, that there are no significant differences in the results from spacecraft positioned at 1 AU. Moreover, the distributions of shock parameters, as well as the shock normal have no significant variations with the heliocentric distance. Additionally, we investigate how the number of shocks associated to stream-interaction regions (SIRs) increases with distance in proportion of ICME/shocks. From 1 to 5 AU, SIRs/ shock occurrence increases slightly from 21% to 34%, in contrast ICME/shocks occurrence decreases from 47% to 17%. We find also indication of an asymmetry induced by the Parker spiral for SIRs and none for ICMEs.

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C. Pérez-Alanis, M. Janvier, T. Nieves-Chinchilla, et. al.
Thu, 13 Apr 23
14/59

Comments: 29 Pages, 11 Figures. Accepted for Publication in Solar Physics

Binary asteroid dissociation and accretion around white dwarfs [EPA]

http://arxiv.org/abs/2304.05579


About 25-50% of white dwarfs (WDs) show metal lines in their spectra. Among the widely accepted explanations for this effect is that the these WDs are accreting asteroids that are perhaps flung onto the WDs by a planet via resonance, for instance. A number of theoretical works have looked into the accretion of asteroids onto WDs and obtained a fair agreement with the observed accretion rate. However, it is solely a very recent study (referenced in this work) that has taken asteroid binarity into consideration, examining the scattering between an asteroid binary and planets and showing that a dissociation and ejection of the former might result and the effect on WD metal accretion is likely to be weak. Here, we investigate the close encounter between an asteroid binary and the central WD and consider how the binary’s dissociation may affect the WD’s accretion. We find that depending on the orbital and physical properties, the components may acquire orbits that are significantly different (even on the order of unity) from that of the parent binary. We assumed all the inner main belt asteroids are binaries and we studied their accretion onto the solar WD under the perturbation of the giant planets. We find that compared to the case without binaries, the components’ accretion may be postponed (or put forward) by millions of years or more, as the objects may be taken out of (or driven deeper into) the resonance due to the sudden orbital change upon dissociation. However, the overall influence of binary dissociation on the accretion rate is not very significant.

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Z. Jin, D. Li and Z. Zhu
Thu, 13 Apr 23
20/59

Comments: 10 pages, 9 figures

Survey of Orion Disks with ALMA (SODA) II: UV-driven disk mass loss in L1641 and L1647 [EPA]

http://arxiv.org/abs/2304.05777


External FUV irradiation of protoplanetary disks has an important impact on their evolution and ability to form planets. However, nearby (<300 pc) star-forming regions lack sufficiently massive young stars, while the Trapezium Cluster and NGC 2024 have complicated star-formation histories and their O-type stars’ intense radiation fields ($>10^4\,G_0$) destroy disks too quickly to study this process in detail. We study disk mass loss driven by intermediate (10 – 1000 $G_0$) FUV radiation fields in L1641 and L1647, where it is driven by more common A0 and B-type stars. Using the large (N=873) sample size offered by the Survey of Orion Disks with ALMA (SODA), we search for trends in the median disk dust mass with FUV field strength across the region as a whole and in two separate regions containing a large number of irradiated disks. For radiation fields between 1 – 100 $G_0$, the median disk mass in the most irradiated disks drops by a factor $\sim 2$ over the lifetime of the region, while the 95th percentile of disk masses drops by a factor 4 over this range. This effect is present in multiple populations of stars, and localized in space, to within 2 pc of ionizing stars. We fit an empirical irradiation – disk mass relation for the first time: $M_{\rm{dust,median}} = -1.3^{+0.14}{-0.13} \log{10}(F_{\rm{FUV}} / G_0) + 5.2^{+0.18}_{-0.19}$. This work demonstrates that even intermediate FUV radiation fields have a significant impact on the evolution of protoplanetary disks.

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S. Terwisga and A. Hacar
Thu, 13 Apr 23
22/59

Comments: Accepted to A&A Letters. 5 pages, 4 figures

Ice, Ice, Maybe? Investigating 46P/Wirtanen's Inner Coma For Icy Grains [EPA]

http://arxiv.org/abs/2304.05953


The release of volatiles from comets is usually from direct sublimation of ices on the nucleus, but for very or hyper-active comets other sources have to be considered to account for the total production rates. In this work, we present new near-infrared imaging and spectroscopic observations of 46P/Wirtanen taken during its close approach to the Earth on 2018 December 19 with the MMIRS instrument at the MMT Observatory to search for signatures of icy or ice-rich grains in its inner coma that might explain its previously reported excess water production. The morphology of the images does not suggest any change in grain properties within the field of view, and the NIR spectra do not show the characteristic absorption features of water ice. Using a new MCMC-based implementation of the spectral modeling approach of Protopapa et al. (2018), we estimate the areal water ice fraction of the coma to be less than 0.6%. When combined with slit-corrected Afrho values for the J, H, and K bands and previously measured dust velocities for this comet, we estimate an icy grain production rate of less than 4.6 kg/s. This places a strict constraint on the water production rate from pure icy grains in the coma, and in turn we find that for the 2018-2019 apparition approximately 64% of 46P’s surface was sublimating water near perihelion. WE then discuss 46P’s modern properties within the context of other (formerly) hyper-active comets to understand how these complex objects evolve.

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T. Kareta, J. Noonan, W. Harris, et. al.
Thu, 13 Apr 23
23/59

Comments: 23 pages, 5 figures, accepted for publication at the Planetary Science Journal on April 10, 2023

A rich hydrocarbon chemistry and high C to O ratio in the inner disk around a very low-mass star [EPA]

http://arxiv.org/abs/2304.05954


Carbon is an essential element for life but how much can be delivered to young planets is still an open question. The chemical characterization of planet-forming disks is a crucial step in our understanding of the diversity and habitability of exoplanets. Very low-mass stars ($<0.2~M_{\odot}$) are interesting targets because they host a rich population of terrestrial planets. Here we present the JWST detection of abundant hydrocarbons in the disk of a very low-mass star obtained as part of the MIRI mid-INfrared Disk Survey (MINDS). In addition to very strong and broad emission from C$_2$H$_2$ and its $^{13}$C$^{12}$CH$_2$ isotopologue, C$_4$H$_2$, benzene, and possibly CH$_4$ are identified, but water, PAH and silicate features are weak or absent. The lack of small silicate grains implies that we can look deep down into this disk. These detections testify to an active warm hydrocarbon chemistry with a high C/O ratio in the inner 0.1 au of this disk, perhaps due to destruction of carbonaceous grains. The exceptionally high C$_2$H$_2$/CO$_2$ and C$_2$H$_2$/H$_2$O column density ratios suggest that oxygen is locked up in icy pebbles and planetesimals outside the water iceline. This, in turn, will have significant consequences for the composition of forming exoplanets.

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B. Tabone, G. Bettoni, E. Dishoeck, et. al.
Thu, 13 Apr 23
48/59

Comments: version submitted to Nature Astronomy

Gap Opening in Protoplanetary Disks: Gas Dynamics from Global Non-ideal MHD Simulations with Consistent Thermochemistry [EPA]

http://arxiv.org/abs/2304.05972


Recent high angular resolution ALMA observations have revealed numerous gaps in protoplanetary disks. A popular interpretation has been that planets open them. Most previous investigations of planet gap-opening have concentrated on viscous disks. Here, we carry out 2D (axisymmetric) global simulations of gap opening by a planet in a wind-launching non-ideal MHD disk with consistent thermochemistry. We find a strong concentration of poloidal magnetic flux in the planet-opened gap, where the gas dynamics are magnetically dominated. The magnetic field also drives a fast (nearly sonic) meridional gas circulation in the denser disk regions near the inner and outer edges of the gap, which may be observable through high-resolution molecular line observations. The gap is more ionized than its denser surrounding regions, with a better magnetic field-matter coupling. In particular, it has a much higher abundance of molecular ion HCO$^+$, consistent with ALMA observations of the well-studied AS 209 protoplanetary disk that has prominent gaps and fast meridional motions reaching the local sound speed. Finally, we provide fitting formulae for the ambipolar and Ohmic diffusivities as a function of the disk local density, which can be used for future 3D simulations of planet gap-opening in non-ideal MHD disks where thermochemistry is too computationally expensive to evolve self-consistently with the magneto-hydrodynamics.

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X. Hu, Z. Li, L. Wang, et. al.
Thu, 13 Apr 23
52/59

Comments: 12 pages, 13 figures, submitted to MNRAS. For animated figures, see: this https URL&list=PLPqbg5l-CV-t-TUePtpv7VtqPL1PHP1U5&ab_channel=FloridaKeys

Deep-learning based measurement of planetary radial velocities in the presence of stellar variability [EPA]

http://arxiv.org/abs/2304.04807


We present a deep-learning based approach for measuring small planetary radial velocities in the presence of stellar variability. We use neural networks to reduce stellar RV jitter in three years of HARPS-N sun-as-a-star spectra. We develop and compare dimensionality-reduction and data splitting methods, as well as various neural network architectures including single line CNNs, an ensemble of single line CNNs, and a multi-line CNN. We inject planet-like RVs into the spectra and use the network to recover them. We find that the multi-line CNN is able to recover planets with 0.2 m/s semi-amplitude, 50 day period, with 8.8% error in the amplitude and 0.7% in the period. This approach shows promise for mitigating stellar RV variability and enabling the detection of small planetary RVs with unprecedented precision.

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I. Colwell, V. Timmaraju and A. Wise
Wed, 12 Apr 23
5/45

Comments: Draft, unsubmitted, 10 pages, 8 figures

Spherical Harmonics for the 1D Radiative Transfer Equation II: Thermal Emission [EPA]

http://arxiv.org/abs/2304.04830


Approximate methods to estimate solutions to the radiative transfer equation are essential for the understanding of atmospheres of exoplanets and brown dwarfs. The simplest and most popular choice is the “two-stream method” which is often used to produce simple yet effective models for radiative transfer in scattering and absorbing media. Toon et al. (1989) (Toon89) outlined a two-stream method for computing reflected light and thermal spectra and was later implemented in the open-source radiative transfer model PICASO. In Part~I of this series, we developed an analytical spherical harmonics method for solving the radiative transfer equation for reflected solar radiation (Rooney et al. 2023), which was implemented in PICASO to increase the accuracy of the code by offering a higher-order approximation. This work is an extension of this spherical harmonics derivation to study thermal emission spectroscopy. We highlight the model differences in the approach for thermal emission and benchmark the 4-term method (SH4) against Toon89 and a high-stream discrete-ordinates method, CDISORT. By comparing the spectra produced by each model we demonstrate that the SH4 method provides a significant increase in accuracy, compared to Toon89, which can be attributed to the increased order of approximation and to the choice of phase function. We also explore the trade-off between computational time and model accuracy. We find that our 4-term method is twice as slow as our 2-term method, but is up to five times more accurate, when compared with CDISORT. Therefore, SH4 provides excellent improvement in model accuracy with minimal sacrifice in numerical expense.

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C. Rooney, N. Batalha and M. Marley
Wed, 12 Apr 23
13/45

Comments: Submitted ApJ; 17 pages; 7 figures; Code available at this https URL; Zenodo release at this https URL; Tutorials/figure reproducibility at this https URL;

Spherical Harmonics for the 1D Radiative Transfer Equation I: Reflected Light [EPA]

http://arxiv.org/abs/2304.04829


A significant challenge in radiative transfer theory for atmospheres of exoplanets and brown dwarfs is the derivation of computationally efficient methods that have adequate fidelity to more precise, numerically demanding solutions. In this work, we extend the capability of the first open-source radiative transfer model for computing the reflected light of exoplanets at any phase geometry, PICASO: Planetary Intensity Code for Atmospheric Spectroscopy Observations. Until now, PICASO has implemented two-stream approaches to the solving the radiative transfer equation for reflected light, in particular following the derivations of Toon et al. (1989) (Toon89). In order to improve the model accuracy, we have considered higher-order approximations of the phase functions, namely, we have increased the order of approximation from 2 to 4, using spherical harmonics. The spherical harmonics approximation decouples spatial and directional dependencies by expanding the intensity and phase function into a series of spherical harmonics, or Legendre polynomials, allowing for analytical solutions for low-order approximations to optimize computational efficiency. We rigorously derive the spherical harmonics method for reflected light and benchmark the 4-term method (SH4) against Toon89 and two independent and higher-fidelity methods (CDISORT & doubling-method). On average, the SH4 method provides an order of magnitude increase in accuracy, compared to Toon89. Lastly, we implement SH4 within PICASO and observe only modest increase in computational time, compared to two-stream methods (20% increase).

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C. Rooney, N. Batalha and M. Marley
Wed, 12 Apr 23
19/45

Comments: Accepted ApJ; 27 pages; 5 figures; Code available at this https URL; Zenodo release at this https URL; Tutorials/figure reproducibility at this https URL

Detection of rubidium and samarium in the atmosphere of the ultra-hot Jupiter MASCARA-4b [EPA]

http://arxiv.org/abs/2304.04948


Ultra-hot Jupiters (UHJs) possess the most extreme environments among various types of exoplanets, making them ideal laboratories to study the chemical composition and kinetics properties of exoplanet atmosphere with high-resolution spectroscopy (HRS). It has the advantage of resolving the tiny Doppler shift and weak signal from exoplanet atmosphere and has helped to detect dozens of heavy elements in UHJs including KELT-9b, WASP-76b, WASP-121b. MASCARA-4b is a 2.8-day UHJ with an equilibrium temperature of $\sim2250$ K, which is expected to contain heavy elements detectable with VLT. In this letter, we present a survey of atoms/ions in the atmosphere of the MASCARA-4b, using the two VLT/ESPRESSO transits data. Cross-correlation analyses are performed on the obtained transmission spectra at each exposure with the template spectra generated by petitRADTRANS for atoms/ions from element Li to U. We confirm the previous detection of Mg, Ca, Cr and Fe and report the detection of Rb, Sm, Ti+ and Ba+ with peak signal-to-noise ratios (SNRs) $>$ 5. We report a tentative detection of Sc+, with peak SNRs $\sim$6 but deviating from the estimated position. The most interesting discovery is the first-time detection of elements Rb and Sm in an exoplanet. Rb is an alkaline element like Na and K, while Sm is the first lanthanide series element and is by far the heaviest one detected in exoplanets. Detailed modeling and acquiring more data are required to yield abundance ratios of the heavy elements and to understand better the common presence of them in UHJ’s atmospheres.

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Z. Jiang, W. Wang, G. Zhao, et. al.
Wed, 12 Apr 23
21/45

Comments: 11 pages, 7 figures, Accepted to AJ

L1 and off Sun-Earth line visible-light imaging of Earth-directed CMEs: An analysis of inconsistent observations [SSA]

http://arxiv.org/abs/2304.05264


The efficacy of coronal mass ejection (CME) observations as a key input to space weather forecasting is explored by comparing on and off Sun-Earth line observations from the ESA/NASA SOHO and NASA STEREO spacecraft. A comparison is made of CME catalogues based on L1 coronagraph imagery and off Sun-Earth line coronagraph and heliospheric imager (HI) observations, for the year 2011. Analysis reveals inconsistencies in the identification of a number of potentially Earth-directed CMEs. The catalogues reflect our ability to identify and characterise CMEs, so any discrepancies can impact our prediction of Earth-directed CMEs. We show that 15 CMEs, which were observed by STEREO, that had estimated directions compatible with Earth-directed events, had no identified halo/partial halo counterpart listed in the L1 coronagraph CME catalogue. In-situ data confirms that for 9 of these there was a consistent L1 Interplanetary CME (ICME). The number of such “discrepant” events is significant compared to the number of ICMEs recorded at L1 in 2011, stressing the need to address space weather monitoring capabilities, particularly with the inclusion of off Sun-Earth line observation. While the study provides evidence that some halo CMEs are simply not visible in near-Earth coronagraph imagery, there is evidence that some halo CMEs viewed from L1 are compromised by preceding CME remnants or the presence of multiple-CMEs. This underlines (1) the value of multiple vantage point CME observation, and (2) the benefit of off Sun-Earth line platform heliospheric imaging, and coronagraph imaging, for the efficient identification and tracking of Earth-directed events.

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R. Harrison, J. Davies, D. Barnes, et. al.
Wed, 12 Apr 23
27/45

Comments: 36 pages, 6 figures, in press at AGU Space Weather, 2023

Rapid solidification of Earth's magma ocean limits early lunar recession [EPA]

http://arxiv.org/abs/2304.04866


The early evolution of the Earth-Moon system prescribes the tidal environment of the Hadean Earth and holds the key to the formation mechanism of the Moon and its thermal evolution. Estimating its early state by backtracking from the present, however, suffers from substantial uncertainties associated with ocean tides. Tidal evolution during the solidification of Earth’s magma ocean, on the other hand, has the potential to provide robust constraints on the Earth-Moon system before the appearance of a water ocean. Here we show that energy dissipation in a solidifying magma ocean results in considerably more limited lunar recession than previously thought, and that the Moon was probably still at the distance of $\sim$7-9 Earth radii at the end of solidification. This limited early recession aggravates the often overlooked difficulty of modeling tidal dissipation in Earth’s first billion years, but it also offers a new possibility of resolving the lunar inclination problem by allowing the operation of multiple excitation mechanisms.

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J. Korenaga
Wed, 12 Apr 23
33/45

Comments: N/A

On the recent discovery claim of a new $z>7$ quasar [GA]

http://arxiv.org/abs/2304.05162


Koptelova et al. 2022 (K22) recently claimed a new quasar discovery at $z=7.46$. After careful consideration of the publicly-available data underlying K22’s claim, we find that the observations were contaminated by a moving Solar System object, likely a main-belt asteroid. In the absence of the contaminated photometry, there is no evidence for the nearby, persistent WISE source being a high-redshift object; in fact, a detection of the source in DELS $z$-band rules out a redshift $z>7.3$. We present our findings as a cautionary tale of the dangers of passing asteroids for photometric selections.

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S. Bosman, F. Davies and E. Bañados
Wed, 12 Apr 23
37/45

Comments: RNAAS; 2 pages, 1 figure

Prediction of Planet Yields by the PRime-focus Infrared Microlensing Experiment Microlensing Survey [EPA]

http://arxiv.org/abs/2304.04605


The PRime-focus Infrared Microlensing Experiment (PRIME) will be the first to conduct a dedicated near infrared (NIR) microlensing survey by using a 1.8m telescope with a wide field of view of 1.45 ${\rm deg^{2}}$ at the South African Astronomical Observatory (SAAO). The major goals of the PRIME microlensing survey are to measure the microlensing event rate in the inner Galactic bulge to help design the observing strategy for the exoplanet microlensing survey by the {\it Nancy Grace Roman Space Telescope} and to make a first statistical measurement of exoplanet demographics in the central bulge fields where optical observations are very difficult owing to the high extinction in these fields. Here we conduct a simulation of the PRIME microlensing survey to estimate its planet yields and determine the optimal survey strategy, using a Galactic model optimized for the inner Galactic bulge. In order to maximize the number of planet detections and the range of planet mass, we compare the planet yields among four observation strategies. Assuming {the \citet{2012Natur.481..167C} mass function as modified by \citet{2019ApJS..241….3P}}, we predict that PRIME will detect planetary signals for $42-52$ planets ($1-2$ planets with $M_p \leq 1 M_\oplus$, $22-25$ planets with mass $1 M_\oplus < M_p \leq 100 M_\oplus$, $19-25$ planets $100 M_\oplus < M_p \leq 10000 M_\oplus$), per year depending on the chosen observation strategy.

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I. Kondo, T. Sumi, N. Koshimoto, et. al.
Tue, 11 Apr 23
2/63

Comments: 25 pages, 17 figures, and 3 tables. Accept for publication in The Astronomical Journal

The infrared colors of 51 Eridani b: micrometereoid dust or chemical disequilibrium? [EPA]

http://arxiv.org/abs/2304.03850


We reanalyze near-infrared spectra of the young extrasolar giant planet 51 Eridani b which was originally presented in (Macintosh et al. 2015) and (Rajan et al. 2017) using modern atmospheric models which include a self-consistent treatment of disequilibrium chemistry due to turbulent vertical mixing. In addition, we investigate the possibility that significant opacity from micrometeors or other impactors in the planet’s atmosphere may be responsible for shaping the observed spectral energy distribution (SED). We find that disequilibrium chemistry is useful for describing the mid-infrared colors of the planet’s spectra, especially in regards to photometric data at M band around 4.5 $\mu$m which is the result of super-equilibrium abundances of carbon monoxide, while the micrometeors are unlikely to play a pivotal role in shaping the SED. The best-fitting, micrometeroid-dust-free, disequilibrium chemistry, patchy cloud model has the following parameters: effective temperature $T_\textrm{eff} = 681$ K with clouds (or without clouds, i.e. the grid temperature $T_\textrm{grid}$ = 900 K), surface gravity $g$ = 1000 m/s$^2$, sedimentation efficiency $f_\textrm{sed}$ = 10, vertical eddy diffusion coefficient $K_\textrm{zz}$ = 10$^3$ cm$^2$/s, cloud hole fraction $f_\textrm{hole}$ = 0.2, and planet radius $R_\textrm{planet}$ = 1.0 R$_\textrm{Jup}$.

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A. Madurowicz, S. Mukherjee, N. Batalha, et. al.
Tue, 11 Apr 23
4/63

Comments: 22 pages, 14 figures, Accepted to AJ

Elemental Abundances of the Super-Neptune WASP-107b's Host Star Using High-resolution, Near-infrared Spectroscopy [EPA]

http://arxiv.org/abs/2304.03808


We present the first elemental abundance measurements of the K dwarf (K7V) exoplanet-host star WASP-107 using high-resolution (R = 45,000), near-infrared (H- and K-band) spectra taken from Gemini-S/IGRINS. We use the previously determined physical parameters of the star from the literature and infer the abundances of 15 elements: C, N, O, Na, Mg, Al, Si, K, Ca, Ti, V, Cr, Mn, Fe, and Ni, all with precision < 0.1 dex, based on model fitting using MARCS model atmospheres and the spectral synthesis code Turbospectrum. Our results show near-solar abundances and a carbon-to-oxygen ratio (C/O) of 0.50 (+/-0.10), consistent with the solar value of 0.54 (+/-0.09). The orbiting planet, WASP-107b, is a super Neptune with a mass in the Neptune regime (= 1.8 M_Nep) and a radius close to Jupiter’s (= 0.94 R_Jup). This planet is also being targeted by four JWST Cycle 1 programs in transit and eclipse, which should provide highly precise measurements of atmospheric abundances. This will enable us to properly compare the planetary and stellar chemical abundances, which is essential in understanding the formation mechanisms, internal structure, and chemical composition of exoplanets. Our study is a proof-of-concept that will pave the way for such measurements to be made for all JWST’s cooler exoplanet-host stars.

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N. Hejazi, I. Crossfield, T. Nordlander, et. al.
Tue, 11 Apr 23
13/63

Comments: 19 pages, 8 figures, Accepted to ApJ

Reducing roundoff errors in numerical integration of planetary ephemeris [EPA]

http://arxiv.org/abs/2304.04458


Modern lunar-planetary ephemerides are numerically integrated on the observational timespan of more than 100 years (with the last 20 years having very precise astrometrical data). On such long timespans, not only finite difference approximation errors, but also the accumulating arithmetic roundoff errors become important because they exceed random errors of high-precision range observables of Moon, Mars, and Mercury. One way to tackle this problem is using extended-precision arithmetics available on x86 processors. Noting the drawbacks of this approach, we propose an alternative: using double-double arithmetics where appropriate. This will allow to use only double precision floating-point primitives which have ubiquitous support.

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M. Subbotin, A. Kodukov and D. Pavlov
Tue, 11 Apr 23
18/63

Comments: N/A

Wavelength-Dependent Extinction and Grain Sizes in Dippers [EPA]

http://arxiv.org/abs/2304.04650


We have examined inter-night variability of K2-discovered Dippers that are not close to being viewed edge-on, as determined from previously-reported ALMA images, using the SpeX spectrograph and the NASA Infrared Telescope facility (IRTF). The three objects observed were EPIC 203850058, EPIC 205151387, and EPIC 204638512 (2MASS J16042165-2130284). Using the ratio of the fluxes between two successive nights, we find that for EPIC 204638512 and EPIC 205151387, we find that the properties of the dust differ from that seen in the diffuse interstellar medium and denser molecular clouds. However, the grain properties needed to explain the extinction does resemble those used to model the disks of many young stellar objects. The wavelength-dependent extinction models of both EPIC 204638512 and EPIC 205151387 includes grains at least 500 microns in size, but lacks grains smaller than 0.25 microns. The change in extinction during the dips, and the timescale for these variations to occur, imply obscuration by the surface layers of the inner disks. The recent discovery of a highly mis-inclined inner disk in EPIC 204638512 is suggests that the variations in this disk system may point to due to rapid changes in obscuration by the surface layers of its inner disk, and that other face-on Dippers might have similar geometries. The He I line at 1.083 microns in EPIC 205151387 and EPIC 20463851 were seen to change from night to night, suggesting that we are seeing He I gas mixed in with the surface dust.

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M. Sitko, R. Russell, Z. Long, et. al.
Tue, 11 Apr 23
24/63

Comments: 13 pages, 6 figures, 2 tables

The GAPS programme at TNG XLV. A massive brown dwarf orbiting the active M dwarf TOI-5375 [SSA]

http://arxiv.org/abs/2304.04477


Context. Massive substellar companions orbiting active low-mass stars are rare. They, however, offer an excellent opportunity to study the main mechanisms involved in the formation and evolution of substellar objects. Aims. We aim to unravel the physical nature of the transit signal observed by the TESS space mission on the active M dwarf TOI-5375. Methods. We analysed the available TESS photometric data as well as high-resolution (R $\sim$ 115000) HARPS-N spectra. We combined these data to characterise the star TOI-5375 and to disentangle signals related to stellar activity from the companion transit signal in the light-curve data. We ran an MCMC analysis to derive the orbital solution and apply state-of-the-art Gaussian process regression to deal with the stellar activity signal. Results. We reveal the presence of a companion in the brown dwarf / very-low-mass star boundary orbiting around the star TOI-5375. The best-fit model corresponds to a companion with an orbital period of 1.721564 $\pm$ 10$^{\rm -6}$ d, a mass of 77 $\pm$ 8 $M_{\rm J}$ and a radius of 0.99 $\pm$ 0.16 $R_{\rm J}$. We derive a rotation period for the host star of 1.9692 $\pm$ 0.0004 d, and we conclude that the star is very close to synchronising its rotation with the orbital period of the companion.

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J. Maldonado, A. Petralia, G. Mantovan, et. al.
Tue, 11 Apr 23
25/63

Comments: Submitted to Astronomy & Astrophysics (under review)

KMT-2021-BLG-2010Lb, KMT-2022-BLG-0371Lb, and KMT-2022-BLG-1013Lb: Three microlensing planets detected via partially covered signals [EPA]

http://arxiv.org/abs/2304.03871


We inspect 4 microlensing events KMT-2021-BLG-1968, KMT-2021-BLG-2010, KMT-2022-BLG-0371, and KMT-2022-BLG-1013, for which the light curves exhibit partially covered short-term central anomalies. We conduct detailed analyses of the events with the aim of revealing the nature of the anomalies. We test various models that can give rise to the anomalies of the individual events including the binary-lens (2L1S) and binary-source (1L2S) interpretations. Under the 2L1S interpretation, we thoroughly inspect the parameter space to check the existence of degenerate solutions, and if they exist, we test the feasibility of resolving the degeneracy. We find that the anomalies in KMT-2021-BLG-2010 and KMT-2022-BLG-1013 are uniquely defined by planetary-lens interpretations with the planet-to-host mass ratios of $q\sim 2.8\times 10^{-3}$ and $\sim 1.6\times 10^{-3}$, respectively. For KMT-2022-BLG-0371, a planetary solution with a mass ratio $q\sim 4\times 10^{-4}$ is strongly favored over the other three degenerate 2L1S solutions with different mass ratios based on the $\chi^2$ and relative proper motion arguments, and a 1L2S solution is clearly ruled out. For KMT-2021-BLG-1968, on the other hand, we find that the anomaly can be explained either by a planetary or a binary-source interpretation, making it difficult to firmly identify the nature of the anomaly. From the Bayesian analyses of the identified planetary events, we estimate that the masses of the planet and host are $(M_{\rm p}/M_{\rm J}, M_{\rm h}/M_\odot) = (1.07^{+1.15}{-0.68}, 0.37^{+0.40}{-0.23})$, $(0.26^{+0.13}{-0.11}, 0.63^{+0.32}{-0.28})$, and $(0.31^{+0.46}{-0.16}, 0.18^{+0.28}{-0.10})$ for KMT-2021-BLG-2010L, KMT-2022-BLG-0371L, and KMT-2022-BLG-1013L, respectively.

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C. Han, C. Lee, W. Zang, et. al.
Tue, 11 Apr 23
34/63

Comments: 12 pages, 17 figures

The Mantis Network III: Expanding the limits of chemical searches within ultra hot-Jupiters. New detections of Ca I, V I, Ti I, Cr I, Ni I, Sr II, Ba II, and Tb II in KELT-9 b [EPA]

http://arxiv.org/abs/2304.04285


Cross-correlation spectroscopy is an invaluable tool in the study of exoplanets. However, aliasing between spectral lines makes it vulnerable to systematic biases. This work strives to constrain the aliases of the cross-correlation function to provide increased confidence in the detections of elements in the atmospheres of ultra-hot Jupiters (UHJs) observed with high-resolution spectrographs. We use a combination of archival transit observations of the UHJ KELT-9 b obtained with the HARPS-N and CARMENES spectrographs and show that it is possible to leverage each instrument’s strengths to produce robust detections at substantially reduced signal-to-noise. Aliases that become present at low signal-to-noise regimes are constrained through a linear regression model. We confirm previous detections of H I, Na I, Mg I, Ca II, Sc II, Ti II, Cr II, Fe I, and Fe II, and detect eight new species Ca I, Cr I, Ni I, Sr II, Tb II at the 5$\sigma$ level and Ti I, V I, Ba II above the 3$\sigma$ level. Ionised terbium (Tb II) has never before been seen in an exoplanet atmosphere. We further conclude that a 5$\sigma$ threshold may not provide a reliable measure of confidence when used to claim detections, unless the systematics in the cross-correlation function caused by aliases are taken into account.

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N. Borsato, H. Hoeijmakers, B. Prinoth, et. al.
Tue, 11 Apr 23
43/63

Comments: Accepted for publication on the 1st of April 2023

Characterisation of the upper atmospheres of HAT-P-32 b, WASP-69 b, GJ 1214 b, and WASP-76 b through their He I triplet absorption [EPA]

http://arxiv.org/abs/2304.03839


Characterisation of atmospheres undergoing photo-evaporation is key to understanding the formation, evolution, and diversity of planets. However, only a few upper atmospheres that experience this kind of hydrodynamic escape have been characterised. Our aim is to characterise the upper atmospheres of the hot Jupiters HAT-P-32 b and WASP-69 b, the warm sub-Neptune GJ 1214 b, and the ultra-hot Jupiter WASP-76 b through high-resolution observations of their HeI triplet absorption. In addition, we also reanalyse the warm Neptune GJ 3470 b and the hot Jupiter HD 189733 b. We used a spherically symmetric 1D hydrodynamic model coupled with a non-local thermodynamic equilibrium model. Comparing synthetic absorption spectra with observations, we constrained the main parameters of the upper atmosphere of these planets and classify them according to their hydrodynamic regime. Our results show that HAT-P-32 b photo-evaporates at (130$\pm$70)$\times$10$^{11}$ gs$^{-1}$ with a hot (12 400$\pm$2900 K) upper atmosphere; WASP-69 b loses its atmosphere at (0.9$\pm$0.5)$\times$10$^{11}$ gs$^{-1}$ and 5250$\pm$750 K; and GJ 1214 b, with a relatively cold outflow of 3750$\pm$750 K, photo-evaporates at (1.3$\pm$1.1)$\times$10$^{11}$ gs$^{-1}$. For WASP-76 b, its weak absorption prevents us from constraining its temperature and mass-loss rate significantly; we obtained ranges of 6000-17 000\,K and 23.5$\pm$21.5$\times$10$^{11}$ gs$^{-1}$. Our reanalysis of GJ 3470 b yields colder temperatures, 3400$\pm$350 K, but practically the same mass-loss rate as in our previous results. Our reanalysis of HD 189733 b yields a slightly higher mass-loss rate, (1.4$\pm$0.5)$\times$10$^{11}$ gs$^{-1}$, and temperature, 12 700$\pm$900 K compared to previous estimates. Our results support that photo-evaporated outflows tend to be very light.

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M. Lampón, M. López-Puertas, J. Sanz-Forcada, et. al.
Tue, 11 Apr 23
45/63

Comments: N/A

Sublimation of ices during the early evolution of Kuiper belt objects [EPA]

http://arxiv.org/abs/2304.04482


Kuiper belt objects, such as Arrokoth, the probable progenitors of short-period comets, formed and evolved at large heliocentric distances, where the ambient temperatures appear to be sufficiently low for preserving volatile ices. By detailed numerical simulations, we follow the long-term evolution of small bodies, composed of amorphous water ice, dust, and ices of other volatile species that are commonly observed in comets. The heat sources are solar radiation and the decay of short-lived radionuclides. The bodies are highly porous and gases released in the interior flow through the porous medium. The most volatile ices, CO and CH$_4$ , are found to be depleted down to the center over a time scale on the order of 100 Myr. Sublimation fronts advance from the surface inward, and when the temperature in the inner part rises sufficiently, bulk sublimation throughout the interior reduces gradually the volatile ices content until they are completely lost. All the other ices survive, which is compatible with data collected by New Horizons on Arrokoth, showing the presence of methanol, and possibly, H$_2$O, CO$_2$, NH$_3$ and C$_2$H$_6$, but no hypervolatiles. The effect of short-lived radionuclides is to increase the sublimation equilibrium temperatures and reduce volatile depletion times. We consider the effect of the bulk density, abundance ratios and heliocentric distance. At 100~au, CO is depleted, but CH$_4$ survives to present time, except for a thin outer layer. Since CO is abundantly detected in comets, we conclude that the source of highly volatile species in active comets must be gas trapped in amorphous ice.

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A. Parhi and D. Prialnik
Tue, 11 Apr 23
46/63

Comments: 8 pages, 7 figures

Jupiter's cloud-level variability triggered by torsional oscillations in the interior [EPA]

http://arxiv.org/abs/2304.04460


Jupiter’s weather layer exhibits long-term and quasi-periodic cycles of meteorological activity that can completely change the appearance of its belts and zones. There are cycles with intervals from 4 to 9 years, dependent on the latitude, which were detected in 5$\mu$m radiation, which provides a window into the cloud-forming regions of the troposphere; however, the origin of these cycles has been a mystery. Here we propose that magnetic torsional oscillations/waves arising from the dynamo region could modulate the heat transport and hence be ultimately responsible for the variability of the tropospheric banding. These axisymmetric waves are magnetohydrodynamic waves influenced by the rapid rotation, which have been detected in Earth’s core, and have been recently suggested to exist in Jupiter by the observation of magnetic secular variations by Juno. Using the magnetic field model JRM33, together with the density distribution model, we compute the expected speed of these waves. For the waves excited by variations in the zonal jet flows, their wavelength can be estimated from the width of the alternating jets, yielding waves with a half period of 3.2-4.7 years in 14-23$^\circ$N, consistent with the intervals with the cycles of variability of Jupiter’s North Equatorial Belt and North Temperate Belt identified in the visible and infrared observations. The nature of these waves, including the wave speed and the wavelength, is revealed by a data-driven technique, dynamic mode decomposition, applied to the spatio-temporal data for 5$\mu$m emission. Our results imply that exploration of these magnetohydrodynamic waves may provide a new window to the origins of quasi-periodic patterns in Jupiter’s tropospheric clouds and to the internal dynamics and the dynamo of Jupiter.

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K. Hori, C. Jones, A. Antuñano, et. al.
Tue, 11 Apr 23
50/63

Comments: N/A

TOI-3785 b: A Low-Density Neptune Orbiting an M2-Dwarf Star [EPA]

http://arxiv.org/abs/2304.04730


Using both ground-based transit photometry and high-precision radial velocity (RV) spectroscopy, we confirm the planetary nature of TOI-3785 b. This transiting Neptune orbits an M2-Dwarf star with a period of ~4.67 days, a planetary radius of 5.14 +/- 0.16 Earth Radii, a mass of 14.95 +4.10, -3.92 Earth Masses, and a density of 0.61 +0.18, -0.17 g/cm^3. TOI-3785 b belongs to a rare population of Neptunes (4 Earth Radii < Rp < 7 Earth Radii) orbiting cooler, smaller M-dwarf host stars, of which only ~10 have been confirmed. By increasing the number of confirmed planets, TOI-3785 b offers an opportunity to compare similar planets across varying planetary and stellar parameter spaces. Moreover, with a high transmission spectroscopy metric (TSM) of ~150 combined with a relatively cool equilibrium temperature of 582 +/- 16 K and an inactive host star, TOI-3785 b is one of the more promising low-density M-dwarf Neptune targets for atmospheric follow-up. Future investigation into atmospheric mass loss rates of TOI-3785 b may yield new insights into the atmospheric evolution of these low-mass gas planets around M-dwarfs.

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L. Powers, J. Libby-Roberts, A. Lin, et. al.
Tue, 11 Apr 23
59/63

Comments: 22 pages, 6 figures, 6 tables, Submitted to AJ

Molecules with ALMA at Planet-forming Scales (MAPS). Complex Kinematics in the AS 209 Disk Induced by a Forming Planet and Disk Winds [EPA]

http://arxiv.org/abs/2304.03665


We study the kinematics of the AS 209 disk using the J=2-1 transitions of $^{12}$CO, $^{13}$CO, and C$^{18}$O. We derive the radial, azimuthal, and vertical velocity of the gas, taking into account the lowered emission surface near the annular gap at ~1.7 (200 au) within which a candidate circumplanetary disk-hosting planet has been reported previously. In $^{12}$CO and $^{13}$CO, we find a coherent upward flow arising from the gap. The upward gas flow is as fast as $150~{\rm m~s}^{-1}$ in the regions traced by $^{12}$CO emission, which corresponds to about 50% of the local sound speed or $6\%$ of the local Keplerian speed. Such an upward gas flow is difficult to reconcile with an embedded planet alone. Instead, we propose that magnetically driven winds via ambipolar diffusion are triggered by the low gas density within the planet-carved gap, dominating the kinematics of the gap region. We estimate the ambipolar Elsasser number, Am, using the HCO$^+$ column density as a proxy for ion density and find that Am is ~0.1 at the radial location of the upward flow. This value is broadly consistent with the value at which numerical simulations find ambipolar diffusion drives strong winds. We hypothesize the activation of magnetically-driven winds in a planet-carved gap can control the growth of the embedded planet. We provide a scaling relationship which describes the wind-regulated terminal mass: adopting parameters relevant to 100 au from a solar-mass star, we find the wind-regulated terminal mass is about one Jupiter mass, which may help explain the dearth of directly imaged super-Jovian-mass planets.

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M. Galloway-Sprietsma, J. Bae, R. Teague, et. al.
Mon, 10 Apr 23
8/36

Comments: N/A

The Disc Miner II: Revealing Gas substructures and Kinematic signatures from Planet-disc interaction through line profile analysis [EPA]

http://arxiv.org/abs/2304.03607


[Abridged] The aim of this work is to identify potential signatures from planet-disc interaction in the circumstellar discs around the young stars MWC 480, HD 163296, AS 209, IM Lup, and GM Aur, through the study of molecular lines observed as part of the ALMA large program MAPS. Extended and localised perturbations in velocity, line width, and intensity have been analysed jointly using the discminer framework, in three bright CO lines, 12CO, 13CO and C18O $J=2-1$, to provide a comprehensive summary of the kinematic and column density substructures that planets might be actively sculpting in these discs. We find convincing evidence for the presence of four giant planets located at wide orbits in three of the discs in the sample: two around HD 163296, one in MWC 480, and one in AS 209. One of the planet candidates in HD 163296, P94, originally proposed by Izquierdo et al. (2022) using lower velocity resolution 12CO data, is confirmed and linked to localised velocity and line width perturbations in 13CO and C18O too. We highlight that line widths are also powerful tracers of planet-forming sites as they are sensitive to turbulent motions triggered by planet-disc interactions. In MWC 480, we identified non-axisymmetric line width enhancements around the radial separation of candidate planet-driven buoyancy spirals proposed by Teague et al. (2021), which we used to narrow the location of the planet candidate to an orbital radius of $R=245$ au and $\rm{PA}=193^\circ$. In the disc of AS 209, we found excess 12CO line widths centred at $R=210$ au, $\rm{PA}=151^\circ$, spanning around the immediate vicinity of the circumplanetary disc candidate proposed by Bae et al. (2022), which further supports its presence. Our simultaneous analysis of multiple tracers and observables aims to lay the groundwork for robust studies of molecular line properties focused on the search for young planets in discs.

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A. Izquierdo, L. Testi, S. Facchini, et. al.
Mon, 10 Apr 23
13/36

Comments: Accepted for publication in A&A

Water Production Rates from SOHO/SWAN Observations of Comets C/2020 S3 (Erasmus), C/2021 A1 (Leonard) and C/2021 O3 (PanSTARRS) [EPA]

http://arxiv.org/abs/2304.03333


In 2021 and 2022 the hydrogen comae of three long period comets, C/2020 S3 (Erasmus), C/2021 A1 (Leonard) and C/2021 O3 (PanSTARRS) were observed with the Solar Wind ANisotropies (SWAN) all-sky hydrogen Lyman-alpha camera on the SOlar and Heliosphere Observer (SOHO) satellite. SWAN obtains nearly daily full-sky images of the hydrogen Lyman-alpha distribution of the interstellar hydrogen as it passes through the solar system yielding information about the solar wind and solar ultraviolet fluxes that eats away at it by ionization and charge exchange. The hydrogen comae of comets, when of sufficient brightness, are also observed. Water production rates have been calculated over time for each of these comets. Of particular interest are comet C/2021 O3 (PanSTARRS) which apparently disintegrated a few days before its perihelion at 0.28 au and C/2021 A1 (Leonard) which also disintegrated beginning about 20 days after its perihelion peak. The behavior of comet C/2020 S3 (Erasmus) was more typical without dramatic fading, but still was asymmetric about perihelion, with a more rapid turn on before perihelion and more extended activity well after perihelion.

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M. Combi, T. Mäkinen, J. Bertaux, et. al.
Mon, 10 Apr 23
16/36

Comments: 20 pages, 4 Figures, 4 Tables

Direct Exoplanet Detection Using L1 Norm Low-Rank Approximation [IMA]

http://arxiv.org/abs/2304.03619


We propose to use low-rank matrix approximation using the component-wise L1-norm for direct imaging of exoplanets. Exoplanet detection is a challenging task for three main reasons: (1) the host star is several orders of magnitude brighter than exoplanets, (2) the angular distance between exoplanets and star is usually very small, and (3) the speckles are very similar to the exoplanet signal both in shape and intensity. First, we empirically examine the statistical noise assumptions of the models, second, we evaluate the performance of the proposed L1 low-rank approximation (L1-LRA) algorithm based on visual comparisons and receiver operating characteristic (ROC) curves. We compare the results of the L1-LRA with the widely used truncated singular value decomposition (SVD) based on the L2 norm in two different annuli, one close to the star and one far away.

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H. Daglayan, S. Vary, V. Leplat, et. al.
Mon, 10 Apr 23
21/36

Comments: 5 pages, 3 figures

The PEPSI Exoplanet Transit Survey. III: The detection of FeI, CrI and TiI in the atmosphere of MASCARA-1 b through high-resolution emission spectroscopy [EPA]

http://arxiv.org/abs/2304.03328


Hot giant planets like MASCARA-1 b are expected to have thermally inverted atmospheres, that makes them perfect laboratory for the atmospheric characterization through high-resolution spectroscopy. Nonetheless, previous attempts of detecting the atmosphere of MASCARA-1 b in transmission have led to negative results.
In this paper we aim at the detection of the optical emission spectrum of MASCARA-1 b.
We used the high-resolution spectrograph PEPSI to observe MASCARA-1 (spectral type A8) near the secondary eclipse of the planet. We cross-correlated the spectra with synthetic templates computed for several atomic and molecular species.
We obtained the detection of FeI, CrI and TiI in the atmosphere of MASCARA-1 b with a S/N ~7, 4 and 5 respectively, and confirmed the expected systemic velocity of ~13 km/s and the radial velocity semi-amplitude of MASCARA-1 b of ~200 km/s. The detection of Ti is of particular importance in the context of the recently proposed Ti cold-trapping below a certain planetary equilibrium temperature.
We confirm the presence of an the atmosphere around MASCARA-1 b through emission spectroscopy. We conclude that the atmospheric non detection in transmission spectroscopy is due to the high gravity of the planet and/or to the overlap between the planetary track and its Doppler shadow.

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G. Scandariato, F. Borsa, A. Bonomo, et. al.
Mon, 10 Apr 23
34/36

Comments: N/A

A Data Science Approach to Study the Water Storage Capacity in Rocky Planet Mantles: Earth, Mars, and Exoplanets [CL]

http://arxiv.org/abs/2304.03700


Nominally anhydrous minerals (NAMs) are the primary carriers of water in rocky planet mantles. Therefore, studying water solubilities of major NAMs in the mantle can help us estimate the water storage capacities of rocky planet mantles and indirectly constrain the actual water contents of their interiors. By using data science methods such as statistics and statistical learning algorithms, in this paper, current modeling studies on the mantle water storage capacities of Earth, Mars, and exoplanets have been introduced and summarized. Firstly, the thermodynamic model for mantle water storage capacity has been reviewed. Then, based on the two case studies on Earth and Mars, how to translate atomic-scale experimental data of water solubility and their measurement errors into planetary-scale models of mantle water storage capacity has been explored by using robust regression, Monte Carlo methods, and bootstrap aggregation algorithms. Thirdly, how the large sample data from the exoplanet observational campaigns can help us understand the statistical properties of the mantle water storage capacities of rocky exoplanets has been introduced. Finally, the application limitations of data science methods in mineral physics research have been discussed, and how to better combine statistics and statistical algorithms with mineral physics data research has been prospected.

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J. Dong
Mon, 10 Apr 23
35/36

Comments: 14 pages, 7 figures, a review article accepted by Bulletin of Mineralogy, Petrology and Geochemistry, in Chinese

The Runaway Greenhouse Effect on Hycean Worlds [EPA]

http://arxiv.org/abs/2304.02698


Hycean worlds are a proposed subset of sub-Neptune exoplanets with substantial water inventories, liquid surface oceans and extended hydrogen-dominated atmospheres that could be favourable for habitability. In this work, we aim to quantitatively define the inner edge of the Hycean habitable zone using a 1D radiative-convective model. As a limiting case, we model a dry hydrogen-helium envelope above a surface ocean. We find that 10 to 20 bars of atmosphere produces enough greenhouse effect to drive a liquid surface ocean supercritical when forced with current Earth-like instellation. Introducing water vapour into the atmosphere, we show the runaway greenhouse instellation limit is greatly reduced due to the presence of superadiabatic layers where convection is inhibited. This moves the inner edge of the habitable zone from $\approx$ 1 AU for a G-star to 1.6 AU (3.85 AU) for a Hycean world with a H$_2$-He inventory of 1 bar (10 bar). For an M-star, the inner edge is equivalently moved from 0.17 AU to 0.28 AU (0.54 AU). Our results suggest that most of the current Hycean world observational targets are not likely to sustain a liquid water ocean. We present an analytical framework for interpreting our results, finding that the maximum possible OLR scales approximately inversely with the dry mass inventory of the atmosphere. We discuss the possible limitations of our 1D modelling and recommend the use of 3D convection-resolving models to explore the robustness of superadiabatic layers.

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H. Innes, S. Tsai and R. Pierrehumbert
Fri, 7 Apr 23
4/50

Comments: Submitted to ApJ, comments welcome

The indication for $^{40}$K geo-antineutrino flux with Borexino phase-III data [CL]

http://arxiv.org/abs/2304.02747


We provide the indication of high flux of $^{40}$K geo-antineutrino and geo-neutrino ($^{40}$K-geo-($\bar{\nu} + \nu$)) with Borexino Phase III data. This result was obtained by introducing a new source of single events, namely $^{40}$K-geo-($\bar{\nu} + \nu$) scattering on electrons, in multivariate fit analysis of Borexino Phase III data. Simultaneously we obtained the count rates of events from $^7$Be, $pep$ and CNO solar neutrinos. These count rates are consistent with the prediction of the Low metallicity Sun model SSM B16-AGSS09. MC pseudo-experiments showed that the case of High metallicity Sun and absence of $^{40}$K-geo-($\bar{\nu} + \nu$) can not imitate the result of multivariate fit analysis of Borexino Phase III data with introducing $^{40}$K-geo-($\bar{\nu} + \nu$) events. We also provide arguments for the high abundance of potassium in the Earth.

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L. Bezrukov, I. Karpikov and V. Sinev
Fri, 7 Apr 23
22/50

Comments: 17 pages, 7 figures. arXiv admin note: substantial text overlap with arXiv:2202.08531

Spectral Type and Geometric Albedo of (98943) 2001 CC21, the Hayabusa2# Mission Target [EPA]

http://arxiv.org/abs/2304.02917


We conducted optical polarimetry and near-infrared spectroscopy of JAXA’s Hayabusa2# mission target, (98943) 2001 CC21, in early 2023. Our new observations indicated that this asteroid has a polarimetric inversion angle of ~21 deg, absorption bands around 0.9 and 1.9 um, and a geometric albedo of 0.285 +- 0.083. All these features are consistent with those of S-type but inconsistent with L-type. Based on this evidence, we conclude that JAXA’s Hayabusa2# spacecraft will explore an S-type asteroid with albedo and size (0.42-0.56 km when we assume the absolute magnitude of 18.6) similar to (25143) Itokawa.

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J. Geem, M. Ishiguro, M. Granvik, et. al.
Fri, 7 Apr 23
27/50

Comments: 5 pages, 3 figures, Submitted to MNRAS Letter on 2023 April 3

Hyades Member K2-136c: The Smallest Planet in an Open Cluster with a Precisely Measured Mass [EPA]

http://arxiv.org/abs/2304.02779


K2-136 is a late-K dwarf ($0.742\pm0.039$ M$\odot$) in the Hyades open cluster with three known, transiting planets and an age of $650\pm70$ Myr. Analyzing K2 photometry, we found that planets K2-136b, c, and d have periods of $8.0$, $17.3$, and $25.6$ days and radii of $1.014\pm0.050$ R$\oplus$, $3.00\pm0.13$ R$\oplus$, and $1.565\pm0.077$ R$\oplus$, respectively. We collected 93 radial velocity measurements (RVs) with the HARPS-N spectrograph (TNG) and 22 RVs with the ESPRESSO spectrograph (VLT). Analyzing HARPS-N and ESPRESSO data jointly, we found K2-136c induced a semi-amplitude of $5.49\pm0.53$ m s$^{-1}$, corresponding to a mass of $18.1\pm1.9$ M$\oplus$. We also placed $95$% upper mass limits on K2-136b and d of $4.3$ and $3.0$ M$\oplus$, respectively. Further, we analyzed HST and XMM-Newton observations to establish the planetary high-energy environment and investigate possible atmospheric loss. K2-136c is now the smallest planet to have a measured mass in an open cluster and one of the youngest planets ever with a mass measurement. K2-136c has $\sim$75% the radius of Neptune but is similar in mass, yielding a density of $3.69^{+0.67}_{-0.56}$ g cm$^{-3}$ ($\sim$2-3 times denser than Neptune). Mass estimates for K2-136b (and possibly d) may be feasible with more RV observations, and insights into all three planets’ atmospheres through transmission spectroscopy would be challenging but potentially fruitful. This research and future mass measurements of young planets are critical for investigating the compositions and characteristics of small exoplanets at very early stages of their lives and providing insights into how exoplanets evolve with time.

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A. Mayo, C. Dressing, A. Vanderburg, et. al.
Fri, 7 Apr 23
29/50

Comments: Accepted in AJ, 25 pages, 10 figures, 5 tables

On Elusive Observations and a Sly Companion of Comet Wirtanen (C/1956 F1) [EPA]

http://arxiv.org/abs/2304.02872


Noting that the extensive astrometric observations of the double comet Wirtanen (C/1956 F1) made by E. Roemer have never been published, I replicate the contents of a fortuitously discovered copy of her measurement records of the companion’s offsets from the main mass in 1957-1959 and use with such data by others to refine the fragmentation solution. The sublimation-driven nongravitational acceleration is shown to essentially control the companion’s motion in the orbital plane. The fragmentation parameters derived by the author in 1978 have now been improved and strong disagreement with the independent results by Roemer is noted. The revised model is employed to predict the positions of the companion on the plates exposed by Roemer on 25 September 1960, which she reported to show the principal nucleus but not the companion. At my request, these plates have now been scanned and processed at the Lowell Observatory, and the companion is found to be located at the predicted position. The images of the main mass and the companion on one of the two plates are displayed.

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Z. Sekanina
Fri, 7 Apr 23
40/50

Comments: 10 pages, 3 figures, 4 tables

High-resolution Emission Spectroscopy of the Ultrahot Jupiter KELT-9b: Little Variation in Day- and Nightside Emission Line Contrasts [EPA]

http://arxiv.org/abs/2304.03248


The transmission spectrum of the ultrahot Jupiter KELT-9b ($T_{eq}$ $\sim$ 4000 K) exhibits absorption by several metal species. We searched for atomic and molecular lines in its emission spectrum by observing partial phase curves with the CARMENES spectrograph ($R$ $\sim$ 80,000 $-$ 95,000). We find evidence for emission by Si I in the atmosphere of KELT-9b for the first time. Additionally we find evidence for emission by Mg I and Ca II, which were previously detected in transmission, and confirmed earlier detections of Fe I emission. Conversely, we find no evidence for dayside emission from Al I, Ca I, Cr I, FeH, Fe II, K I, Li I, Mg II, Na I, OH, Ti I, TiO, V I, V II, VO, and Y I. By employing likelihood mapping, we find indications of there being little variation in emission line contrast between the day- and nightsides $-$suggesting that KELT-9b may harbor iron emission on its nightside. Our results demonstrate that high-resolution ground-based emission spectroscopy can provide valuable insights into exoplanet atmospheres.

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A. Ridden-Harper, E. Mooij, R. Jayawardhana, et. al.
Fri, 7 Apr 23
41/50

Comments: Accepted for publication in AJ

Photometry of outer Solar System objects from the Dark Energy Survey I: photometric methods, light curve distributions and trans-Neptunian binaries [EPA]

http://arxiv.org/abs/2304.03017


We report the methods of and initial scientific inferences from the extraction of precision photometric information for the $>800$ trans-Neptunian objects (TNOs) discovered in the images of the Dark Energy Survey (DES). Scene-modelling photometry is used to obtain shot-noise-limited flux measures for each exposure of each TNO, with background sources subtracted. Comparison of double-source fits to the pixel data with single-source fits are used to identify and characterize two binary TNO systems. A Markov Chain Monte Carlo method samples the joint likelihood of the intrinsic colors of each source as well as the amplitude of its flux variation, given the time series of multiband flux measurements and their uncertainties. A catalog of these colors and light curve amplitudes $A$ is included with this publication. We show how to assign a likelihood to the distribution $q(A)$ of light curve amplitudes in any subpopulation. Using this method, we find decisive evidence (i.e. evidence ratio $<0.01$) that cold classical (CC) TNOs with absolute magnitude $6<H_r<8.2$ are more variable than the hot classical (HC) population of the same $H_r$, reinforcing theories that the former form in situ and the latter arise from a different physical population. Resonant and scattering TNOs in this $H_r$ range have variability consistent with either the HC’s or CC’s. DES TNOs with $H_r<6$ are seen to be decisively less variable than higher-$H_r$ members of any dynamical group, as expected. More surprising is that detached TNOs are decisively less variable than scattering TNOs, which requires them to have distinct source regions or some subsequent differential processing.

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P. Bernardinelli, G. Bernstein, N. Jindal, et. al.
Fri, 7 Apr 23
43/50

Comments: Submitted to AAS journals, data release forthcoming and will be included in journal version

MOA-2022-BLG-249Lb: Nearby microlensing super-Earth planet detected from high-cadence surveys [EPA]

http://arxiv.org/abs/2304.02815


We investigate the data collected by the high-cadence microlensing surveys during the 2022 season in search for planetary signals appearing in the light curves of microlensing events. From this search, we find that the lensing event MOA-2022-BLG-249 exhibits a brief positive anomaly that lasted for about 1 day with a maximum deviation of $\sim 0.2$~mag from a single-source single-lens model. We analyze the light curve under the two interpretations of the anomaly: one originated by a low-mass companion to the lens (planetary model) and the other originated by a faint companion to the source (binary-source model). It is found that the anomaly is better explained by the planetary model than the binary-source model. We identify two solutions rooted in the inner–outer degeneracy, for both of which the estimated planet-to-host mass ratio, $q\sim 8\times 10^{-5}$, is very small. With the constraints provided by the microlens parallax and the lower limit on the Einstein radius, as well as the blend-flux constraint, we find that the lens is a planetary system, in which a super-Earth planet, with a mass $(4.83\pm 1.44)~M_\oplus$, orbits a low-mass host star, with a mass $(0.18\pm 0.05)~M_\odot$, lying in the Galactic disk at a distance $(2.00\pm 0.42)$~kpc. The planet detection demonstrates the elevated microlensing sensitivity of the current high-cadence lensing surveys to low-mass planets.

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C. Han, A. Gould, Y. Jung, et. al.
Fri, 7 Apr 23
46/50

Comments: 10 pages, 9 figures

Eccentric Dust Ring in the IRS 48 Transition Disk [SSA]

http://arxiv.org/abs/2304.02937


Crescent-shaped structures in transition disks hold the key to studying the putative companions to the central stars. The dust dynamics, especially that of different grain sizes, is important to understanding the role of pressure bumps in planet formation. In this work, we present deep dust continuum observation with high resolution towards the Oph IRS 48 system. For the first time, we are able to significantly trace and detect emission along $95\%$ of the ring crossing the crescent-shaped structure. The ring is highly eccentric with an eccentricity of $0.27$. The flux density contrast between the peak of the flux and its counter part along the ring is $\sim 270$. In addition, we detect a compact emission toward the central star. If the emission is an inner circumstellar disk inside the cavity, it has a radius of at most a couple of astronomical units with a dust mass of $1.5\times 10^{-8}\rm\, M_\odot$, or $0.005\rm\, M_\oplus$. We also discuss the implications of the potential eccentric orbit on the proper motion of the crescent, the putative secondary companion, and the asymmetry in velocity maps.

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H. Yang, M. Fernandez-Lopez, Z. Li, et. al.
Fri, 7 Apr 23
47/50

Comments: 9 pages, 5 figures, accepted for publication on AAS Journals

Intra-system uniformity: a natural outcome of dynamical sculpting [EPA]

http://arxiv.org/abs/2304.02634


There is evidence that exoplanet systems display intra-system uniformity in mass, radius, and orbital spacing (like “peas in a pod”) when compared with the system-to-system variations of planetary systems. This has been interpreted as the outcome of the early stages of planet formation, indicative of a picture in which planets form at characteristic mass scales with uniform separations. In this paper, we argue instead that intra-system uniformity in planet sizes and orbital spacings likely arose from the long-term dynamical sculpting of initially-overly-packed planetary systems (in other words, the giant impact phase). With a suite of $N$-body simulations, we demonstrate that systems with random initial masses and compact planet spacings naturally develop intra-system uniformity, in quantitative agreement with observations, due to collisions between planets. Our results suggest that the pre-giant impact planet mass distribution is fairly wide and provide evidence for the prevalence of dynamical sculpting in shaping the observed population of exoplanets.

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C. Lammers, N. Murray and S. Hadden
Thu, 6 Apr 23
4/76

Comments: 5 pages, 5 figures. Submitted to MNRAS Letters

The Lense-Thirring effect on the Galilean moons of Jupiter [CL]

http://arxiv.org/abs/2304.02289


The perspectives of detecting the general relativistic Lense-Thirring effect on the orbits of the Galilean moons of Jupiter induced by its angular momentum ${\boldsymbol{S}}$ are preliminarily investigated. Numerical integrations over one century show that the expected gravitomagnetic signatures of some observables such as the satellites’ right ascension $\alpha$ and declination $\delta$ are as large as tens of arcseconds for Io, while for Callisto they drop to the $\simeq 0.2\,\mathrm{arcseconds}$ level; the shifts in the transverse component $T$ of the orbit range from 40 km for Io to 2 km for Callisto. Major competing effects due to the mismodeling in the zonal multipoles $J_\ell,\,\ell=2,\,3,\,4,\,\ldots$ of the Jovian non-spherically symmetric gravity field and in the Jupiter’s spin axis ${\boldsymbol{\hat{k}}}$ should have a limited impact, especially in view of the future improvements in determing such parameters expected after the completion of the ongoing Juno mission in the next few years. Present-day accuracy in knowing the orbits of Io, Europa, Ganymede and Callisto is of the order of 10 milliarcseconds, to be likely further improved by the approved JUICE and Clipper missions. This suggests that the Lense-Thirring effect in the main Jovian system of moons might be detectable with dedicated data reductions in which the gravitomagnetic field is explicitly modeled and solved-for.

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L. Iorio
Thu, 6 Apr 23
8/76

Comments: LaTex2e, 24 pages, 12 figures, no tables

Identifying and characterizing ultracool dwarfs ejected from post-encounter disintegrating systems [SSA]

http://arxiv.org/abs/2304.02236


Disintegrating multiple systems have been previously discovered from kinematic studies of the $\it Hipparcos$ catalogue. They are presumably the result of dynamical encounters taking place in the Galactic disk between single/multiple systems. In this paper, we aim to expand the search for such systems, to study their properties, as well as to characterize possible low-mass ejecta (i.e. brown dwarfs and planets). We have assembled a list of 15 candidate systems using astrometry from the Tycho-Gaia astrometric solution (later upgraded with $\it Gaia$ DR3), and here we present the discovery and follow-up of 5 of them. We have obtained DECam imaging for all 5 systems and by combining near-infrared photometry and proper motion, we searched for ultra-cool ejected components. We find that the system consisting of TYC 7731-1951-1, TYC 7731-2128 AB, and TYC 7731-1995-1ABC?, contains one very promising ultra-cool dwarf candidate. Using additional data from the literature, we have found that 3 out of 5 disintegrating system candidates are likely to be true disintegrating systems.

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A. Yip, R. Kurtev, D. Pinfield, et. al.
Thu, 6 Apr 23
10/76

Comments: Accepted for publication in MNRAS. 17 pages, 8 figures, 4 tables

Accretion of aerodynamically large pebbles [EPA]

http://arxiv.org/abs/2304.02044


Due to their aerodynamical coupling with gas, pebbles in protoplanetary discs can drift over large distances to support planet growth in the inner disc. In the past decade, this pebble accretion has been studied extensively for aerodynamically small pebbles (Stokes number St < 1). However, accretion can also operate in the St > 1 mode, e.g., when planetesimals collisionally fragment to smaller bodies or when the primordial gas disc disperses. This work aims to extend the study of pebble accretion to these aerodynamically loosely coupled particles. We integrate the pebble’s equation of motion, accounting for gas drag, stellar and planetary gravity, in the midplane of a laminar disc. The accretion probability ($\epsilon$) is calculated as function of Stokes number, disc pressure gradient index, planet mass and eccentricity. We find that for Stokes number above unity $\epsilon$(St) first rises, due to lower drift and aided by a large atmospheric capture radius, until it reaches a plateau where the efficiency approaches 100 per cent. At high St the plateau region terminates as particles become trapped in resonance. These results are well described by a semi-analytical “kick-and-drift” model and we also provide fully analytical prescriptions for $\epsilon$. We apply our model to the accretion of $\sim 30 \mu$m dust particles in a dispersing protoplanetary and secondary (CO-rich) debris disc. It shows that physically small particles are mainly accreted as aerodynamically large Stokes number pebbles during the debris disc phase. Earth-mass planets may obtain $\sim 25$ per cent of their heavy elements through this late accretion phase.

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H. Huang and C. Ormel
Thu, 6 Apr 23
15/76

Comments: 19 pages, 16 figures, 5 tables. Accepted for publication in MNRAS

On the correct computation of all Lyapunov exponents in Hamiltonian dynamical systems [GA]

http://arxiv.org/abs/2304.02503


The Lyapunov Characteristic Exponents are a useful indicator of chaos in astronomical dynamical systems. They are usually computed through a standard, very efficient and neat algorithm published in 1980. However, for Hamiltonian systems the expected result of pairs of opposite exponents is not always obtained with enough precision. We find here why in these cases the initial order of the deviation vectors matters, and how to sort them in order to obtain a correct result.

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D. Carpintero and J. Muzzio
Thu, 6 Apr 23
18/76

Comments: 8 pages, 3 figures

G 68-34: A Double-Lined M-Dwarf Eclipsing Binary in a Hierarchical Triple System [SSA]

http://arxiv.org/abs/2304.02466


Using high-resolution spectra from the Tillinghast Reflector Echelle Spectrograph (TRES) and photometry from sector 56 of the Transiting Exoplanet Survey Satellite (TESS), we report that the nearby M dwarf G 68-34 is a double-lined eclipsing binary. The pair is spin-orbit synchronized with a period of 0.655 days. The light curve shows significant spot modulation with a larger photometric amplitude than that of the grazing eclipses. We perform a joint fit to the spectroscopic and photometric data, obtaining masses of $0.3280\pm 0.0034$M$\odot$ and $0.3207\pm 0.0036$M$\odot$ and radii of $0.345\pm 0.014$R$\odot$ and $0.342\pm 0.014$R$\odot$ after marginalizing over unknowns in the starspot distribution. This system adds to the small but growing population of fully convective M dwarfs with precisely measured masses and radii that can be used to test models of stellar structure. The pair also has a white dwarf primary at 9″ separation, with the system known to be older than 5 Gyr from the white-dwarf cooling age. The binarity of G 68-34 confirms our hypothesis from Pass et al. (2022): in that work, we noted that G 68-34 was both rapidly rotating and old, highly unusual given our understanding of the spindown of M dwarfs, and that a close binary companion may be responsible.

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E. Pass and D. Charbonneau
Thu, 6 Apr 23
32/76

Comments: Accepted for publication in ApJ, 10 pages, 5 figures, 3 tables

The influence of cold Jupiters in the formation of close-in planets. I. planetesimal transport [EPA]

http://arxiv.org/abs/2304.02045


The formation of a cold Jupiter (CJ) is expected to quench the influx of pebbles and the migration of cores interior to its orbit, thus limiting the efficiency of rocky planet formation either by pebble accretion and/or orbital migration. Observations, however, show that the presence of outer CJs ( >1 au and >0.3 Jupiter masses) correlates with the presence of inner Super Earths (at <1 au). This observation may simply be a result of an enhanced initial reservoir of solids in the nebula required to form a CJ or a yet-to-be-determined mechanism assisted by the presence of the CJ. In this work, we focus on the latter alternative and study the orbital transport of planetesimals interior to a CJ subject to the gravity and drag from a viscously-evolving gaseous disk. We find that a secular resonance sweeping inwards through the disk gradually transports rings of planetesimals when their drag-assisted orbital decay is faster than the speed of the resonance scanning. This snowplow-like process leads to large concentration (boosted by a factor of ~10-100) of size-segregated planetesimal rings with aligned apsidal lines, making their expected collisions less destructive due to their reduced velocity dispersion. This process is efficient for a wide range of alpha-disk models and Jovian masses, peaking for ~1-5 Jupiter masses, typical of observed CJs in radial velocity surveys. Overall, our work highlights the major role that the disk’s gravity may have on the orbital redistribution of planetesimals, depicting a novel avenue by which CJs may enhance the formation of inner planetary systems, including super-Earths and perhaps even warm and hot Jupiters.

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S. Best, A. Sefilian and C. Petrovich
Thu, 6 Apr 23
34/76

Comments: 18 pages, 11 figures

Geometric Solution to the Angles-Only Initial Orbit Determination Problem [EPA]

http://arxiv.org/abs/2304.02157


Initial orbit determination (IOD) from line-of-sight (i.e., bearing) measurements is a classical problem in astrodynamics. Indeed, there are many well-established methods for performing the IOD task when given three line-of-sight observations at known times. Interestingly, and in contrast to these existing methods, concepts from algebraic geometry may be used to produce a purely geometric solution. This idea is based on the fact that bearings from observers in general position may be used to directly recover the shape and orientation of a three-dimensional conic (e.g., a Keplerian orbit) without any need for knowledge of time. In general, it is shown that five bearings at unknown times are sufficient to recover the orbit — without the use of any type of initial guess and without the need to propagate the orbit. Three bearings are sufficient for purely geometric IOD if the orbit is known to be (approximately) circular. The method has been tested over different scenarios, including one where extra observations make the system of equations over-determined.

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M. Mancini, T. Duff, A. Leykin, et. al.
Thu, 6 Apr 23
42/76

Comments: 31 pages excluding back matter, 14 figures

Three long period transiting giant planets from TESS [EPA]

http://arxiv.org/abs/2304.02139


We report the discovery and orbital characterization of three new transiting warm giant planets. These systems were initially identified as presenting single transit events in the light curves generated from the full frame images of the Transiting Exoplanet Survey Satellite (TESS). Follow-up radial velocity measurements and additional light curves were used to determine the orbital periods and confirm the planetary nature of the candidates. The planets orbit slightly metal-rich late F- and early G-type stars. We find that TOI 4406b has a mass of $M_P$= 0.30 $\pm$ 0.04 $M_J$ , a radius of $R_P$= 1.00 $\pm$ 0.02 $R_J$ , and a low eccentricity orbit (e=0.15 $\pm$ 0.05) with a period of P= 30.08364 $\pm$ 0.00005 d . TOI 2338b has a mass of $M_P$= 5.98 $\pm$ 0.20 $M_J$ , a radius of $R_P$= 1.00 $\pm$ 0.01 $R_J$ , and a highly eccentric orbit (e= 0.676 $\pm$ 0.002 ) with a period of P= 22.65398 $\pm$ 0.00002 d . Finally, TOI 2589b has a mass of $M_P$= 3.50 $\pm$ 0.10 $M_J$ , a radius of $R_P$= 1.08 $\pm$ 0.03 $R_J$ , and an eccentric orbit (e = 0.522 $\pm$ 0.006 ) with a period of P= 61.6277 $\pm$ 0.0002 d . TOI 4406b and TOI 2338b are enriched in metals compared to their host stars, while the structure of TOI 2589b is consistent with having similar metal enrichment to its host star.

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R. Brahm, S. Ulmer-Moll, M. Hobson, et. al.
Thu, 6 Apr 23
43/76

Comments: 24 pages, 16 figures, accepted in AJ

Modelling the optical energy profile of the 2021 October Jupiter impact flash [EPA]

http://arxiv.org/abs/2304.02184


We have conducted numerical simulations to reproduce the observed optical energy profile of the 15 October 2021 (UT) impact flash on Jupiter, which was the largest and the most well-observed flash event detected by ground-based movie observations. The observed long-duration ($\sim 5.5~{\rm s}$) optical emission can be reproduced by an impact of an object with an exceptionally small angle of entry relative to the horizontal. The apparent lack of the impact debris feature despite the large impact object was possibly due to the shallower angle of entry ($\le 12^\circ$), which resulted in the lower ablation per unit volume at altitudes higher than $50 \, {\rm km}$, and the volume densities of the ablated materials were too low to allow the debris particulates to coagulate. The absence of temporal methane absorption change in the observed flash spectrum is consistent with the best-fit results. The model better fits the observed optical energy profile for weaker material (cometary and stony) cases than for metallic ones. Based on the simulation results, prospects for future observations of impact flashes are discussed.

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K. Arimatsu, K. Tsumura, F. Usui, et. al.
Thu, 6 Apr 23
63/76

Comments: 6 pages, 5 figures, Accepted for publication in MNRAS

Dynamical Mass of the Young Brown Dwarf Companion PZ Tel B [SSA]

http://arxiv.org/abs/2304.01302


Dynamical masses of giant planets and brown dwarfs are critical tools for empirically validating substellar evolutionary models and their underlying assumptions. We present a measurement of the dynamical mass and an updated orbit of PZ Tel B, a young brown dwarf companion orbiting a late-G member of the $\beta$ Pic moving group. PZ Tel A exhibits an astrometric acceleration between Hipparcos and Gaia EDR3, which enables the direct determination of the companion’s mass. We have also acquired new Keck/NIRC2 adaptive optics imaging of the system, which increases the total baseline of relative astrometry to 15 years. Our joint orbit fit yields a dynamical mass of $27^{+25}{-9} \, M{\mathrm{Jup}}$, semi-major axis of $27^{+14}{-4} \, \mathrm{au}$, eccentricity of $0.52^{+0.08}{-0.10}$, and inclination of $91.73^{+0.36}_{-0.32} {}^\circ$. The companion’s mass is consistent within $1.1\sigma$ of predictions from four grids of hot-start evolutionary models. The joint orbit fit also indicates a more modest eccentricity of PZ Tel B than previous results. PZ Tel joins a small number of young (${<}200 \, \mathrm{Myr}$) systems with benchmark substellar companions that have dynamical masses and precise ages from moving group membership.

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K. Franson and B. Bowler
Wed, 5 Apr 23
27/62

Comments: 14 pages, 5 figures, accepted to AJ

Revisiting the Red-giant Branch Hosts KOI-3886 and $ι$ Draconis. Detailed Asteroseismic Modeling and Consolidated Stellar Parameters [SSA]

http://arxiv.org/abs/2304.01570


Asteroseismology is playing an increasingly important role in the characterization of red-giant host stars and their planetary systems. Here, we conduct detailed asteroseismic modeling of the evolved red-giant branch (RGB) hosts KOI-3886 and $\iota$ Draconis, making use of end-of-mission Kepler (KOI-3886) and multi-sector TESS ($\iota$ Draconis) time-series photometry. We also model the benchmark star KIC 8410637, a member of an eclipsing binary, thus providing a direct test to the seismic determination. We test the impact of adopting different sets of observed modes as seismic constraints. Inclusion of $\ell=1$ and 2 modes improves the precision on the stellar parameters, albeit marginally, compared to adopting radial modes alone, with $1.9$-$3.0\%$ (radius), $5$-$9\%$ (mass), and $19$-$25\%$ (age) reached when using all p-dominated modes as constraints. Given the very small spacing of adjacent dipole mixed modes in evolved RGB stars, the sparse set of observed g-dominated modes is not able to provide extra constraints, further leading to highly multimodal posteriors. Access to multi-year time-series photometry does not improve matters, with detailed modeling of evolved RGB stars based on (lower-resolution) TESS data sets attaining a precision commensurate with that based on end-of-mission Kepler data. Furthermore, we test the impact of varying the atmospheric boundary condition in our stellar models. We find mass and radius estimates to be insensitive to the description of the near-surface layers, at the expense of substantially changing both the near-surface structure of the best-fitting models and the values of associated parameters like the initial helium abundance, $Y_{\rm i}$. Attempts to measure $Y_{\rm i}$ from seismic modeling of red giants may thus be systematically dependent on the choice of atmospheric physics.

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T. Campante, T. Li, J. Ong, et. al.
Wed, 5 Apr 23
31/62

Comments: Accepted for publication in The Astronomical Journal (AJ)

The Hamiltonian for von Zeipel-Lidov-Kozai oscillations [EPA]

http://arxiv.org/abs/2304.01257


The Hamiltonian used in classical analyses of von Zeipel-Lidov-Kozai or ZLK oscillations in hierarchical triple systems is based on the quadrupole potential from a distant body on a fixed orbit, averaged over the orbits of both the inner and the outer bodies (“double-averaging”). This approximation can be misleading, because the corresponding Hamiltonian conserves the component of angular momentum of the inner binary normal to the orbit of the outer binary, thereby restricting the volume of phase space that the system can access. This defect is usually remedied by including the effects of the octopole potential, or by allowing the outer orbit to respond to variations in the inner orbit. However, in a wide variety of astrophysical systems nonlinear perturbations are comparable to or greater than these effects. The long-term effects of nonlinear perturbations are described by an additional Hamiltonian, which we call Brown’s Hamiltonian. At least three different forms of Brown’s Hamiltonian are found in the literature; we show that all three are related by a gauge freedom, although one is much simpler than the others. We argue that investigations of ZLK oscillations in triple systems should include Brown’s Hamiltonian.

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S. Tremaine
Wed, 5 Apr 23
32/62

Comments: 11 pages, 3 figures. To be published in Monthly Notices of the Royal Astronomical Society

How to form compact & other longer-lived planet-induced vortices: VSI, planet migration, or re-triggers, but not feedback [EPA]

http://arxiv.org/abs/2304.01674


Past computational studies of planet-induced vortices have shown that the dust asymmetries associated with these vortices can be long-lived enough that they should be much more common in mm/sub-mm observations of protoplanetary discs, even though they are quite rare. Observed asymmetries also have a range of azimuthal extents from compact to elongated even though computational studies have shown planet-induced vortices should be preferentially elongated. In this study, we use 2-D and 3-D hydrodynamic simulations to test whether those dust asymmetries should really be so long-lived or so elongated. With higher resolution (29 cells per scale height) than our previous work, we find that vortices can be more compact by developing compact cores when higher-mass planets cause them to re-form, or if they are seeded by tiny compact vortices from the vertical shear instability (VSI), but not through dust feedback in 3-D as was previously expected in general. Any case with a compact vortex or core(s) also has a longer lifetime. Even elongated vortices can have longer lifetimes with higher-mass planets or if the associated planet is allowed to migrate, the latter of which can cause the dust asymmetry to stop decaying as the planet migrates away from the vortex. These longer dust asymmetry lifetimes are even more inconsistent with observations, perhaps suggesting that discs still have an intermediate amount of effective viscosity.

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M. Hammer and M. Lin
Wed, 5 Apr 23
34/62

Comments: 24 pages, 21 figures; Submitted to MNRAS

LHS 475 b: A Venus-sized Planet Orbiting a Nearby M Dwarf [EPA]

http://arxiv.org/abs/2304.01920


Based on photometric observations by TESS, we present the discovery of a Venus-sized planet transiting LHS 475, an M3 dwarf located 12.5 pc from the Sun. The mass of the star is $0.274 \pm 0.015~\rm{M_{Sun}}$. The planet, originally reported as TOI 910.01, has an orbital period of $2.0291025 \pm 0.0000020$ days and an estimated radius of $0.955 \pm 0.053~\rm{R_{Earth}}$. We confirm the validity and source of the transit signal with MEarth ground-based follow-up photometry of five individual transits. We present radial velocity data from CHIRON that rule out massive companions. In accordance with the observed mass-radius distribution of exoplanets as well as planet formation theory, we expect this Venus-sized companion to be terrestrial, with an estimated RV semi-amplitude close to 1.0 m/s. LHS 475 b is likely too hot to be habitable but is a suitable candidate for emission and transmission spectroscopy.

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K. Ment, D. Charbonneau, J. Irwin, et. al.
Wed, 5 Apr 23
35/62

Comments: 17 pages, 5 figures, submitted to AJ

Prediction of solar wind speed by applying convolutional neural network to potential field source surface (PFSS) magnetograms [SSA]

http://arxiv.org/abs/2304.01234


An accurate solar wind speed model is important for space weather predictions, catastrophic event warnings, and other issues concerning solar wind – magnetosphere interaction. In this work, we construct a model based on convolutional neural network (CNN) and Potential Field Source Surface (PFSS) magnetograms, considering a solar wind source surface of $R_{\rm SS}=2.5R_\odot$, aiming to predict the solar wind speed at the Lagrange 1 (L1) point of the Sun-Earth system. The input of our model consists of four Potential Field Source Surface (PFSS) magnetograms at $R_{\rm SS}$, which are 7, 6, 5, and 4 days before the target epoch. Reduced magnetograms are used to promote the model’s efficiency. We use the Global Oscillation Network Group (GONG) photospheric magnetograms and the potential field extrapolation model to generate PFSS magnetograms at the source surface. The model provides predictions of the continuous test dataset with an averaged correlation coefficient (CC) of 0.52 and a root mean square error (RMSE) of 80.8 km/s in an eight-fold validation training scheme with the time resolution of the data as small as one hour. The model also has the potential to forecast high speed streams of the solar wind, which can be quantified with a general threat score of 0.39.

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R. Lin, Z. Luo, J. He, et. al.
Wed, 5 Apr 23
39/62

Comments: N/A

Testing protoplanetary disc evolution with CO fluxes. A proof of concept in Lupus and Upper Sco [EPA]

http://arxiv.org/abs/2304.01760


The Atacama Large Millimeter/submillimeter Array (ALMA) revolutionised our understanding of protoplanetary discs. However, the available data have not given conclusive answers yet on the underlying disc evolution mechanisms (viscosity or MHD winds). Improving upon the current results, mostly based on the analysis of disc sizes, is difficult because larger, deeper and higher angular resolution surveys would be required, which could be prohibitive even for ALMA. In this Letter, we introduce an alternative method to study disc evolution based on $^{12}$CO fluxes. In fact, fluxes can be readily collected using less time-consuming, lower resolution observations, while tracing the same disc physico-chemical processes as sizes: assuming that $^{12}$CO is optically thick, fluxes scale with the disc surface area. We developed a semi-analytical model to compute $^{12}$CO fluxes and benchmarked it against the results of DALI thermochemical models, recovering an agreement within a factor of three. As a proof of concept we compared our models with Lupus and Upper Sco data, taking advantage of the increased samples, by a factor 1.3 (Lupus) and 3.6 (Upper Sco), when studying fluxes instead of sizes. Models and data agree well only if CO depletion is considered. However, the uncertainties on the initial conditions limited our interpretation of the observations. Our new method can be used to design future ad hoc observational strategies to collect better data and give conclusive answers on disc evolution.

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F. Zagaria, S. Facchini, A. Miotello, et. al.
Wed, 5 Apr 23
43/62

Comments: 10 pages, 9 figures; accepted for publication in A&A Letters. Code and data available at this https URL

The orbit of Aegaeon and the 7:6 Mimas-Aegaeon resonance [EPA]

http://arxiv.org/abs/2304.01923


Aegaeon (S/2008 S 1) is the last satellite discovered by the Cassini spacecraft at the end of the 2000s. Like the satellites Methone and Anthe, it is involved in mean motion resonance with the mid-sized Mimas. In this work, we give a detailed analysis of the current orbit of Aegaeon identifying the resonant, secular and long-term perturbations due to Mimas and the oblateness of Saturn, and the effects of Tethys. For this task, we perform thousands of numerical simulations of full equations of motion of ensembles of small bodies representing clones of Aegaeon. We have mapped the domain of the 7:6 Mimas-Aegaeon resonance in the phase space of the semi-major axis and eccentricity. It displays a large area dominated by regular motions associated with the 7:6 corotation resonance surrounded by chaotic layers. Aegaeon is currently located very close to the periodic orbit of the resonance, which extends up to eccentricities $\sim0.025$ centered at semi-major axis $\sim168,028$ km. We show that the current orbit of Aegaeon has an important forced component in eccentricity due to the 7:6 resonance. The orbital inclination of Aegaeon has a non-negligible forced value due to long-term perturbations of Mimas. These two forced modes explain the complex perturbed orbit of Aegaeon without requiring the co-existence of multiple resonances.

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N. Jr. and A. Rodríguez
Wed, 5 Apr 23
47/62

Comments: 24 pages, 8 figures

On a Super-Complete Mathematical Model of Ambipolar Processes of Cumulation and Dissipation in Self-Focusing Structures in Plasma of Planetary Atmospheres in plasma with current [CL]

http://arxiv.org/abs/2304.01231


4D mathematical models of structurally related (conjugated, entangled, dual) phenomena of dissipation and cumulation of electrical energy (an external source in continuous media) are discussed, accompanied by the formation of cumulative-dissipative structures and their ordering into a regular system – a dynamic dissipative “crystal” with a long-range dynamic order. The excitation of new degrees of freedom in such systems provides attractiveness or geometric self-focusing of energy-mass-momentum flows (EMMF) for the entire regular system. As a result of cumulation, EMMF structures acquire hyper-properties. The cumulation of EMMF in rendered structures is a common property of media activated to form 4D structures. The basis of such a dissipative structure is an attractor, the end result of which is a cumulative jet from an attractor with hyper-properties. Therefore, these structures are cumulative-dissipative. We discuss a method for describing these structures and prove that cumulative processes in plasmoids exist and can be described theoretically, although not with the help of full-fledged mathematical 4D models. It has been theoretically and experimentally proven that the cumulation of the electric field due to the ambipolar drift of the plasma is an inherent property of the current carrying gas-discharge plasma. The results obtained by modeling shock waves of the electric field (E/N) can be useful to explain the cumulative formation in the heliosphere, atmosphere and ionosphere of the Earth, since the Earth has a negative charge of about 500,000 C, and the Sun positively charged at the level of 1400 C. Based on the mathematical approach, a classification of shock waves and types of cumulation in 4D space-time will be carried out.

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P. Vysikaylo
Wed, 5 Apr 23
52/62

Comments: 5 pages, 4 figures, this https URL

Approaches for Retrieving Sulfur Species Abundances from Dual X/Ka Band Radio Occultations of Venus with EnVision and VERITAS [EPA]

http://arxiv.org/abs/2304.02006


The EnVision and VERITAS missions to Venus will fly with X and Ka band telecommunications channels which can be used to conduct radio occultation studies of Venus’ atmosphere. While link attenuation measurements during prior S and X band occultation experiments have been used to determine vertical profiles of H$_2$SO$_4$ vapor abundance, the addition of the Ka band channel introduces greater sensitivity to the abundances of H$_2$SO$_4$ aerosols and SO$_2$ gas, permitting retrieval of their vertical profiles from dual band measurements. Such measurements would be valuable in the assessment of chemical and dynamical processes governing short and long-term variability in Venus’ atmosphere. This paper considers the sensitivity of the X/Ka band radio attenuation measurement to these atmospheric constituents, as well as uncertainties and regularization approaches for conducting retrievals of these atmospheric sulfur species from future occultation experiments. We introduce methods for seeding maximum likelihood estimation retrievals using shape models and simple atmospheric transport constraints. From simulated retrievals, we obtain mean errors of the order of 0.5 ppm, 20 ppm, and 10 mg/m$^3$ for H$_2$SO$_4$ vapor, SO$_2$, and H$_2$SO$_4$ aerosol abundances, respectively, for simultaneous retrieval.

Read this paper on arXiv…

A. Akins, T. Bocanegra-Bahamón, K. Wang, et. al.
Wed, 5 Apr 23
60/62

Comments: 29 pages, 11 figures, accepted to PSJ