Trapping planets in an evolving protoplanetary disk: preferred time, locations, and planet mass
IMCCE, Observatoire de Paris, PSL Research University, CNRS, Sorbonne
Univ. Lille 1, 77 Av.
2 Institut de Physique du Globe, Sorbonne Paris Cité, Université Paris Diderot/CNRS, 1 rue Jussieu, 75005 Paris, France
3 Laboratoire AIM-LADP, Université Paris Diderot/CEA/CNRS, 91191 Gif-sur-Yvette, France
Received: 22 December 2015
Accepted: 23 March 2016
Context. Planet traps are necessary to prevent forming planets from falling onto their host star by type I inward migration. Surface mass density and temperature gradient irregularities favor the apparition of traps (planet accumulation region) and deserts (planet depletion zone). These features are found at the dust sublimation lines and heat transition barriers.
Aims. We study how planets may remain trapped or escape these traps as they grow and as the disk evolves viscously with time.
Methods. We numerically model the temporal viscous evolution of a protoplanetary disk by coupling its dynamics, thermodynamics, geometry, and composition. The resulting midplane density and temperature profiles allow the modeling of the interactions of this type of evolving disk with potential planets, even before the steady state is reached.
Results. We follow the viscous evolution of a minimum mass solar nebula and compute the Lindblad and corotation torques that this type of disk would exert on potential planets of various masses that are located within the planetary formation region. We determine the position of planet traps and deserts in relationship with the sublimation lines, shadowed regions, and heat transition barriers. We notice that the planet mass affects the trapping potential of the mentioned structures through the saturation of the corotation torque. Planets that are a few tens of Earth masses can be trapped at the sublimation lines until they reach a certain mass while planets that are more massive than 100 M⊕ can only be trapped permanently at the heat transition barriers. They may also open gaps beyond 5 au and enter type II migration.
Conclusions. Coupling a bimodal planetary migration model with a self-consistent evolved disk, we were able to distinguish several potential planet populations after five million years of evolution: two populations of giant planets that could stay trapped around 5.5 and 9 au and possibly open gaps, some super-Earths trapped around 5 and 7.5 au, and a population of close-in super-Earths, which are trapped inside 1 au. The traps that correspond to the last group could help to validate the in situ formation scenarios of the observed close-in super-Earths.
Key words: protoplanetary disks / planets and satellites: formation / planets and satellites: dynamical evolution and stability / planet-disk interactions / accretion, accretion disks / hydrodynamics
© ESO, 2016