Resonant Trapping of Planetesimals by Planet Migration: Debris Disk Clumps and Vega’s Similarity to the Solar System

Astrophysics, abstract
astro-ph/0308253

From: Mark Wyatt <wyatt@roe.ac.uk>

Date: Thu, 14 Aug 2003 16:41:14 GMT   (217kb)

Authors:
M. C. Wyatt (UKATC, Royal Observatory Edinburgh)

Comments: 30 pages, accepted by ApJ

This paper describes a model which can explain the observed clumpy structures
of debris disks. Clumps arise because after a planetary system forms its
planets migrate due to angular momentum exchange with the remaining
planetesimals. Outward migration of the outermost planet traps planetesimals
outside its orbit into its resonances and resonant forces cause azimuthal
structure in their distribution. The model is based on numerical simulations of
planets of different masses, Mpl, migrating at different rates, dapl/dt,
through a dynamically cold (e<0.01) planetesimal disk initially at a semimajor
axis a. Trapping probabilities and the resulting azimuthal structures are
presented for a planet’s 2:1, 5:3, 3:2, and 4:3 resonances. Seven possible
dynamical structures are identified from migrations defined by mu=Mpl/Mstar and
theta=dapl/dt*sqrt(a/Mstar). Application of this model to the 850um image of
Vega’s disk shows its two clumps of unequal brightness can be explained by the
migration of a Neptune-mass planet from 40 to 65AU over 56Myr; tight
constraints are set on possible ranges of these parameters. The clumps are
caused by planetesimals in the 3:2 and 2:1 resonances; the asymmetry arises
because of the overabundance of planetesimals in the 2:1(u) over the 2:1(l)
resonance. The similarity of this migration to that proposed for our own
Neptune hints that Vega’s planetary system may be much more akin to the solar
system than previously thought. Predictions are made which would substantiate
this model, such as the orbital motion of the clumpy pattern, the location of
the planet, and the presence of lower level clumps.

References and citations for this submission:

SLAC-SPIRES HEP (refers to ,
cited by, arXiv reformatted)