Planet formation and migration near the silicate sublimation front in protoplanetary disks. (arXiv:1910.03901v1 [astro-ph.EP])
<a href="http://arxiv.org/find/astro-ph/1/au:+Flock_M/0/1/0/all/0/1">Mario Flock</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Turner_N/0/1/0/all/0/1">Neal J. Turner</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Mulders_G/0/1/0/all/0/1">Gijs D. Mulders</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Hasegawa_Y/0/1/0/all/0/1">Yasuhiro Hasegawa</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Nelson_R/0/1/0/all/0/1">Richard P. Nelson</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Bitsch_B/0/1/0/all/0/1">Bertram Bitsch</a>
The increasing number of newly detected exoplanets at short orbital periods
raises questions about their formation and migration histories. A particular
puzzle that requires explanation arises from one of the key results of the
Kepler mission, namely the increase in the planetary occurrence rate with
orbital period up to 10 days for F, G, K and M stars. We investigate the
conditions for planet formation and migration near the dust sublimation front
in protostellar disks around young Sun-like stars. For this analysis we use
iterative 2D radiation hydrostatic disk models which include irradiation by the
star, and dust sublimation and deposition depending on the local temperature
and vapor pressure. We perform a parameter study by varying the magnetized
turbulence onset temperature, the accretion stress, the dust mass fraction, and
the mass accretion rate. Our models feature a gas-only inner disk, a silicate
sublimation front and dust rim starting at around 0.08 au, an ionization
transition zone with a corresponding density jump, and a pressure maximum which
acts as a pebble trap at around 0.12 au. Migration torque maps show Earth- and
super-Earth-mass planets halt in our model disks at orbital periods ranging
from 10 to 22 days. Such periods are in good agreement with both the inferred
location of the innermost planets in multiplanetary systems, and the break in
planet occurrence rates from the Kepler sample at 10 days. In particular,
models with small grains depleted produce a trap located at a 10-day orbital
period, while models with a higher abundance of small grains present a trap at
around a 17-day orbital period. The snow line lies at 1.6 au, near where the
occurrence rate of the giant planets peaks. We conclude that the dust
sublimation zone is crucial for forming close-in planets, especially when
considering tightly packed super-Earth systems.
The increasing number of newly detected exoplanets at short orbital periods
raises questions about their formation and migration histories. A particular
puzzle that requires explanation arises from one of the key results of the
Kepler mission, namely the increase in the planetary occurrence rate with
orbital period up to 10 days for F, G, K and M stars. We investigate the
conditions for planet formation and migration near the dust sublimation front
in protostellar disks around young Sun-like stars. For this analysis we use
iterative 2D radiation hydrostatic disk models which include irradiation by the
star, and dust sublimation and deposition depending on the local temperature
and vapor pressure. We perform a parameter study by varying the magnetized
turbulence onset temperature, the accretion stress, the dust mass fraction, and
the mass accretion rate. Our models feature a gas-only inner disk, a silicate
sublimation front and dust rim starting at around 0.08 au, an ionization
transition zone with a corresponding density jump, and a pressure maximum which
acts as a pebble trap at around 0.12 au. Migration torque maps show Earth- and
super-Earth-mass planets halt in our model disks at orbital periods ranging
from 10 to 22 days. Such periods are in good agreement with both the inferred
location of the innermost planets in multiplanetary systems, and the break in
planet occurrence rates from the Kepler sample at 10 days. In particular,
models with small grains depleted produce a trap located at a 10-day orbital
period, while models with a higher abundance of small grains present a trap at
around a 17-day orbital period. The snow line lies at 1.6 au, near where the
occurrence rate of the giant planets peaks. We conclude that the dust
sublimation zone is crucial for forming close-in planets, especially when
considering tightly packed super-Earth systems.
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