Identifying inflated super-Earths and photo-evaporated cores

Daniel Carrera, Eric B. Ford, Andre Izidoro, Daniel Jontof-Hutter, Sean N. Raymond, Angie Wolfgang
(Submitted on 13 Apr 2018)

We present empirical evidence, supported by a planet formation model, to show that the curve $R/R_\oplus = 1.05\,(F/F_\oplus)^{0.11}$ approximates the location of the so-called photo-evaporation valley. Planets below that curve are likely to have experienced complete photoevaporation. Furthermore, planets just above this curve appear to have inflated radii; thus we identify a new population of inflated super-Earths and mini-Neptunes. Our N-body simulations are set within an evolving protoplanetary disk and include prescriptions for orbital migration, gas accretion and atmospheric loss due to giant impacts. Our simulated systems broadly match the sizes and periods of super-Earths in the Kepler catalog. They also match the relative sizes of adjacent planets in the same system, with the exception of planet pairs that straddle the photo-evaporation valley. This latter group is populated by planet pairs with either very large or very small size ratios ($R_{\rm out} / R_{\rm in} \gg 1$ or $R_{\rm out} / R_{\rm in} \ll 1$) and a dearth of size ratios near unity. It appears that this feature could be reproduced if the planet outside the photoevaporation valley (typically the outer planet, but some times not) is substantially inflated. This new population of inflated planets may be ideal targets for future transit spectroscopy observations with the upcoming James Webb Space Telescope.

Comments:    21 pages, 10 figures, submitted to ApJ
Subjects:    Earth and Planetary Astrophysics (astro-ph.EP)
Cite as:    arXiv:1804.05069 [astro-ph.EP] (or arXiv:1804.05069v1 [astro-ph.EP] for this version)
Submission history
From: Daniel Carrera
[v1] Fri, 13 Apr 2018 18:00:05 GMT (1006kb,D)
https://arxiv.org/abs/1804.05069