Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Planetesimal-driven planet migration in the presence of a gas disk   We report here on an extension of a previous study by Kirsh et al. (2009) of
planetesimal-driven migration using our N-body code SyMBA (Duncan et al.,
1998). The previous work focused on the case of a single planet of mass Mem,
immersed in a planetesimal disk with a power-law surface density distribution
and Rayleigh distributed eccentricities and inclinations. Typically 10^4-10^5
equal-mass planetesimals were used, where the gravitational force (and the
back-reaction) on each planetesimal by the Sun and planetwere included, while
planetesimal-planetesimal interactions were neglected. The runs reported on
here incorporate the dynamical effects of a gas disk, where the Adachi et al.
(1976) prescription of aerodynamic gas drag is implemented for all bodies. In
some cases the Papaloizou and Larwood (2000) prescription of Type-I migration
for the planet are implemented, as well as a mass distribution. In the gas-free
cases, rapid planet migration was observed - at a rate independent of the
planet's mass - provided the planet's mass was not large compared to the mass
in planetesimals capable of entering its Hill sphere. In such cases, both
inward and outward migrations can be self-sustaining, but there is a strong
propensity for inward migration. When a gas disk is present, aerodynamic drag
can substantially modify the dynamics of scattered planetesimals. For
sufficiently large or small mono-dispersed planetesimals, the planet typically
migrates inward. However, for a range of plausible planetesimal sizes (i.e.
0.5-5.0 km at 5.0 AU in a minimum mass Hayashi disk) outward migration is
usually triggered, often accompanied by substantial planetary mass accretion.
The origins of this behaviour are explained in terms of a toy model. The
effects of including a size distribution and torques associated with Type-I
migration are also discussed.

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The categories of this paper are: cmp-lg
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The categories of this paper are: q-bio
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The categories of this paper are: eess
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The categories of this paper are: stat
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The categories of this paper are: atom-ph
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The categories of this paper are: nlin
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The categories of this paper are: hep-ex
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The categories of this paper are: ao-sci
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The categories of this paper are: plasm-ph
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The categories of this paper are: alg-geom
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The categories of this paper are: acc-phys
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The categories of this paper are: gr-qc
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The categories of this paper are: cs
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The categories of this paper are: supr-con
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The categories of this paper are: math-ph
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The categories of this paper are: dg-ga