SETI public: Planetary migration

• Previous message: LARRY KLAES: "SETI public: Atmosphere, Interior, and Evolution of the Metal-Rich Transiting Planet HD 14902"

Paper: astro-ph/0507492
Date: Wed, 20 Jul 2005 21:06:43 GMT (344kb)

Title: Planetary migration

Authors: Philip J. Armitage, W. K. M. Rice

Comments: To appear in proceedings, "A Decade Of Extrasolar Planets Around
Normal Stars", STScI May Symposium 2005. Accompanying animation of migration
regimes at http://jilawww.colorado.edu/~pja/planet_migration.html
\\
Gravitational torques between a planet and gas in the protoplanetary disk
result in orbital migration of the planet, and are likely to play an
important
role in the formation and early evolution of planetary systems. For masses
comparable to those of observed giant extrasolar planets, the interaction
with
the disk is strong enough to form a gap, leading to coupled evolution of the
planet and disk on a viscous time scale (Type II migration). Both the
existence
of hot Jupiters, and the statistical distribution of observed orbital radii,
are consistent with an important role for Type II migration in the history
of
currently observed systems. We discuss the possibility of improving
constraints
on migration by including information on the host stars' metallicity, and
note
that migration could also form a population of massive planets at large
orbital
radii that may be indirectly detected via their influence on debris disks.
For
lower mass planets with masses of the order of that of the Earth, surface
density perturbations created by the planet are small, and migration in a
laminar disk is driven by an intrinsic and apparently robust asymmetry
between
interior and exterior torques. Analytic and numerical calculations of this
Type
I migration are in reasonable accord, and predict rapid orbital decay during
the final stages of the formation of giant planet cores. The difficulty of
reconciling Type I migration with giant planet formation may signal basic
errors in our understanding of protoplanetary disks, core accretion, or
both.
We discuss physical effects that might alter Type I behavior, in particular
the
possibility that for sufficiently low masses turbulent fluctuations in the
gas
surface density dominate the torque, leading to random walk migration of
very
low mass bodies.

\\ ( http://arXiv.org/abs/astro-ph/0507492 , 344kb)

• Previous message: LARRY KLAES: "SETI public: Atmosphere, Interior, and Evolution of the Metal-Rich Transiting Planet HD 14902"

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