TY - JOUR

T1 - Forming giant planets around late-M dwarfs

T2 - Pebble accretion and planet-planet collision

AU - Pan, Mengrui

AU - Liu, Beibei

AU - Johansen, Anders

AU - Ogihara, Masahiro

AU - Wang, Su

AU - Ji, Jianghui

AU - Wang, Sharon X.

AU - Feng, Fabo

AU - Ribas, Ignasi

N1 - Publisher Copyright: © The Authors 2024.

PY - 2024

Y1 - 2024

N2 - We propose a pebble-driven core accretion scenario to explain the formation of giant planets around the late-M dwarfs of M∗=0.1-0.2 M⊙. In order to explore the optimal disk conditions for giant planet, we performed N-body simulations to investigate the growth and dynamical evolution of both single and multiple protoplanets in the disks with both inner viscously heated and outer stellar irradiated regions. The initial masses of the protoplanets are either assumed to be equal to 0.01 M⊕ or calculated based on the formula derived from streaming instability simulations. Our findings indicate that massive planets are more likely to form in disks with longer lifetimes, higher solid masses, moderate to high levels of disk turbulence, and larger initial masses of protoplanets. In the single protoplanet growth cases, the highest planet core mass that can be reached is generally lower than the threshold necessary to trigger rapid gas accretion, which impedes the formation of giant planets. Nonetheless, in multi-protoplanet cases, the cores can exceed the pebble isolation mass barrier aided by frequent planet-planet collisions. This consequently speeds their gas accretion up and promotes giant planet formation, making the optimal parameter space to grow giant planets substantially wider. Taken together, our results suggest that even around very-low-mass stellar hosts, the giant planets with orbital periods of ≤100 days are still likely to form when lunar-mass protoplanets first emerge from planetesimal accretion and then grow rapidly by a combination of pebble accretion and planet-planet collisions in disks with a high supply of a pebble reservoir >50 M⊕ and a turbulent level of αt ~ 10-3-10-2.

AB - We propose a pebble-driven core accretion scenario to explain the formation of giant planets around the late-M dwarfs of M∗=0.1-0.2 M⊙. In order to explore the optimal disk conditions for giant planet, we performed N-body simulations to investigate the growth and dynamical evolution of both single and multiple protoplanets in the disks with both inner viscously heated and outer stellar irradiated regions. The initial masses of the protoplanets are either assumed to be equal to 0.01 M⊕ or calculated based on the formula derived from streaming instability simulations. Our findings indicate that massive planets are more likely to form in disks with longer lifetimes, higher solid masses, moderate to high levels of disk turbulence, and larger initial masses of protoplanets. In the single protoplanet growth cases, the highest planet core mass that can be reached is generally lower than the threshold necessary to trigger rapid gas accretion, which impedes the formation of giant planets. Nonetheless, in multi-protoplanet cases, the cores can exceed the pebble isolation mass barrier aided by frequent planet-planet collisions. This consequently speeds their gas accretion up and promotes giant planet formation, making the optimal parameter space to grow giant planets substantially wider. Taken together, our results suggest that even around very-low-mass stellar hosts, the giant planets with orbital periods of ≤100 days are still likely to form when lunar-mass protoplanets first emerge from planetesimal accretion and then grow rapidly by a combination of pebble accretion and planet-planet collisions in disks with a high supply of a pebble reservoir >50 M⊕ and a turbulent level of αt ~ 10-3-10-2.

KW - methods: numerical

KW - planets and satellites: dynamical evolution and stability

KW - planets and satellites: formation

KW - planets and satellites: gaseous planets

U2 - 10.1051/0004-6361/202347664

DO - 10.1051/0004-6361/202347664

M3 - Journal article

AN - SCOPUS:85184952111

VL - 682

JO - Astronomy & Astrophysics

JF - Astronomy & Astrophysics

SN - 0004-6361

M1 - A89

ER -