Destructive Feedback in ExoPlanets

Tidal Downsizing Model. IV. Destructive feedback in planets

Author:

Nayakshin

Abstract:

I argue that feedback is as important to formation of planets as it is to formation of stars and galaxies. Energy released by massive solid cores puffs up pre-collapse gas giant planets, making them vulnerable to tidal disruptions by their host stars. I find that feedback is the ultimate reason for some of the most robust properties of the observed exoplanet populations: the rarity of gas giants at all separations from ∼0.1 to ∼100~AU, the abundance of ∼10M⊕ cores but dearth of planets more massive than ∼20M⊕. Feedback effects can also explain (i) rapid assembly of massive cores at large separations as needed for Uranus, Neptune and the suspected HL Tau planets; (ii) the small core in Jupiter yet large cores in Uranus and Neptune; (iii) the existence of rare "metal monster" planets such as CoRoT-20b, a gas giant made of heavy elements by up to ∼50\%.