Volume 663, July 2022
|Number of page(s)||15|
|Section||Planets and planetary systems|
|Published online||05 July 2022|
Gas disk interactions, tides and relativistic effects in the rocky planet formation at the substellar mass limit
Facultad de Ciencias Astronómicas y Geofísicas, Universidad Nacional de La Plata,
Paseo del Bosque s/n,
2 Instituto de Astrofísica de La Plata, CCT La Plata-CONICET-UNLP, Paseo del Bosque s/n, 1900 La Plata, Argentina
3 Departamento de Astronomía, Facultad de Ciencias, Universidad de la República, Iguá 4225, 14000 Montevideo, Uruguay
Accepted: 24 March 2022
Context. The confirmed exoplanet population around very low mass stars is increasing considerable through data from the latest space missions and improvements in ground-based observations, particularly with the detection of Earth-like planets in the habitable zones. However, theoretical models need to improve in the study of planet formation and evolution around low-mass hosts.
Aims. Our main goal is to study the formation of rocky planets and the first 100 Myr of their dynamical evolution around a star with a mass of 0.08 M⊙, which is close to the substellar mass limit.
Methods. We developed two sets of N-body simulations assuming an embryo population affected by tidal and general relativistic effects, refined by the inclusion of the spin-up and contraction of the central star. This population is immersed in a gas disk during the first 10 Myr. Each set of simulations incorporated a different prescription from the literature to calculate the interaction between the gas-disk and the embryos: one widely used prescription which is based on results from hydrodynamics simulations, and a recent prescription that is based on the analytic treatment of dynamical friction.
Results. We found that in a standard disk model, the dynamical evolution and the final architectures of the resulting rocky planets are strongly related with the prescription used to treat the interaction within the gas and the embryos. Its impact on the resulting close-in planet population and particularly on those planets that are located inside the habitable zone is particularly strong.
Conclusions. The distribution of the period ratio of adjacent confirmed exoplanets observed around very low mass stars and brown dwarfs and the exoplanets that we obtained from our simulations agrees well only when the prescription based on dynamical friction for gas-embryo interaction was used. Our results also reproduce a close-in planet population of interest that is located inside the habitable zone. A fraction of these planets will be exposed for a long period of time to the stellar irradiation inside the inner edge of the evolving habitable zone until the zone reaches them.
Key words: planets and satellites: terrestrial planets / planets and satellites: formation / stars: low-mass / planet-disk interactions / planet-star interactions / methods: numerical
© ESO 2022
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