Dust Settling and Rapid Planetary Migration

Abstract

Planetary migration is essential to explain the observed mass-period relation for exoplanets. Without some stopping mechanism, the tidal, resonant interaction between planets and their gaseous disc generally causes the planets to migrate inward so efficiently that they plunge into the host star within the gaseous disc lifetime ($\sim$ 1-3 Myrs). We investigate planetary migration by analytically calculating the migration rate and time within self-consistently computed, radiatively heated discs around M stars in which the effects of dust settling are included. We show that dust settling lowers the disc temperature and raises the gas density in the mid-plane. This inescapable evolution of disc structure speeds up type I planetary migration for lower mass bodies by up to a factor of about 2. We also examine the effects of dust settling on the gap-opening mass and type II migration, and find that the gap-opening mass is reduced by a factor of 2 and type II migration becomes slower by a factor of 2. While dust settling can somewhat alleviate the problem of planetary migration for more massive planets, the more rapid migration of low mass planets and planetary cores requires a robust slowing mechanism.

16 pages, 13 figures, 3 tables, accepted for publication in MNRAS

References in corpus (10)

• Gas- and dust evolution in protoplanetary disks
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• On the corotation torque in a radiatively inefficient disk
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Cited by in corpus (11)

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• Evolutionary Tracks of Trapped, Accreting Protoplanets: the Origin of the Observed Mass-Period Relation
• Time evolution of snow regions and planet traps in an evolving protoplanetary disk
• The Origin of Heavy Element Content Trend in Giant Planets via Core Accretion
• Trapping planets in an evolving protoplanetary disk: preferred time, locations and planet mass
• Probing Dust Settling in Proto-planetary Disks with ALMA
• Super-Earths as Failed Cores in Orbital Migration Traps
• Turbulent Disk Viscosity and the Bifurcation of Planet Formation Histories
• Building protoplanetary disks from the molecular cloud: redefining the disk timeline
• The Properties of Planetesimal Collisions under Jupiter's Perturbation and the Application to Chondrule Formation via Impact Jetting
• Dead Zones and the Diversity of Exoplanetary Systems