Journal Article

Dust settling and rapid planetary migration

Yasuhiro Hasegawa and Ralph E. Pudritz

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 413, issue 1, pages 286-300
Published in print May 2011 | ISSN: 0035-8711
Published online April 2011 | e-ISSN: 1365-2966 | DOI: http://dx.doi.org/10.1111/j.1365-2966.2010.18135.x
Dust settling and rapid planetary migration

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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 (∼1–3 Myr). 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.

Keywords: accretion, accretion discs; radiative transfer; turbulence; methods: analytical; planet-disc interactions; protoplanetary discs

Journal Article.  11431 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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