Abstract

I will present new results about the dynamics of hot protoplanets embedded in a gaseous medium with thermal diffusion. The release of heat by a luminous planet into the surrounding gas induces a perturbation of density that gives rise to a contribution to the gravitational force exerted on the planet. Called thermal force, this contribution can take various forms depending on the planet’s trajectory and on the gas flow. For a body traversing a gas at rest on a linear trajectory, the thermal force is opposed to the standard dynamical friction, and can yield a net acceleration of the body if the latter is sufficiently luminous. In the case of a planet on a circular orbit in a protoplanetary disc, thermal forces usually tend to counteract inward migration. When the planet’s luminosity is above a certain threshold, they also tend to excite the planet’s eccentricity and inclination to values comparable to the aspect ratio of the disc. Finally, I will present results from N-body calculations of a collection of pebble accreting embryos, for which the effects of thermal forces are incorporated. Compared to more standard calculations in which these effects are neglected, they tend to produce, over the 1 Myr time span of our runs, planets that have a markedly smaller dispersion of masses.