http://arxiv.org/abs/1901.01435
We validate the planetary origin of the KOI-1599 transit time variations (TTVs) with statistical and dynamical tests. We re-analysed KEPLER Q1-Q17 light-curves of the star, and we independently derived the TTVs. They appear as strongly anti-correlated, suggestive of two mutually interacting planets. We found similar radii of the candidates, $1.9 \pm 0.2\, \mbox{R}{\oplus}$ for the inner KOI-1599.02, and $1.9 \pm 0.3\, \mbox{R}{\oplus}$ for the outer KOI-1599.01. The standard MCMC TTV analysis constrains the planet masses safely below the dynamical instability limit of $\simeq 3\, \mbox{M}{\mbox{Jup} } $. The best-fitting MCMC model yields $(9.0\pm0.3)\,\mbox{M}{\oplus}$, and $(4.6\pm0.3)\,\mbox{R}{\oplus}$, for the inner and the outer planet, respectively. The planets are trapped in 3:2 mean motion resonance (MMR) with anti-aligned apsides ($\Delta \varpi = 180^{\circ}$) at low-eccentric ($e\simeq 0.01)$ orbits. However, we found that the TTV mass determination depends on eccentricity priors with the dispersion in the (0.01,0.05) range. They permit a second family of TTV models with smaller masses of $\simeq 7\,\mbox{M}{\oplus}$, and $\simeq 3.6\,\mbox{M}_{\oplus}$, respectively, exhibiting two modes of $\Delta \varpi = 0^{\circ},180^{\circ}$ librations. The 3:2 MMR is dynamically robust and persists for both modes. In order to resolve the mass duality, we re-analysed the TTV data with a quasi-analytic model of resonant TTV signals. This model favours the smaller masses. We also reproduced this model with simulating the migration capture of the system into the 3:2 MMR.
F. Panichi, C. Migaszewski and K. Goździewski
Tue, 8 Jan 19
25/99
Comments: 16 pages, 13 figures, submitted to Monthly Notices of the RAS
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