MIGRATION RATES OF PLANETS DUE TO SCATTERING OF PLANETESIMALS

Journal Article · Sat Oct 20 04:00:00 EDT 2012 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/758/2/80· OSTI ID:22086545

Ormel, C W ^[1]; Ida, S ^[2]; Tanaka, H ^[3]

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1. Astronomy Department, University of California, Berkeley, CA 94720 (United States)
2. Department of Earth and Planetary Sciences, Tokyo Institute of Technology, Meguro-ku, Tokyo 152-8551 (Japan)
3. Institute of Low Temperature Science, Hokkaido University, Sapporo 060-0819 (Japan)

Planets migrate due to the recoil they experience from scattering solid (planetesimal) bodies. To first order, the torques exerted by the interior and exterior disks will cancel, analogous to the cancellation of the torques from the gravitational interaction with the gas (Type-I migration). Assuming the dispersion-dominated regime and power laws characterized by indices {alpha} and {beta} for the surface density and eccentricity profiles, we calculate the net torque on the planet. We consider both distant encounters and close (orbit-crossing) encounters. We find that the close and distant encounter torques have opposite signs with respect to {alpha} and {beta}; and that the torque is especially sensitive to the eccentricity gradient {beta}. Compared to Type-I migration due to excitation of density waves, the planetesimal-driven migration rate is generally lower due to the lower surface density of solids in gas-rich disk, although this may be partially or fully offset when their eccentricity and inclinaton are small. Allowing for the feedback of the planet on the planetesimal disk through viscous stirring, we find that under certain conditions a self-regulated migration scenario emerges, in which the planet migrates at a steady pace that approaches the rate corresponding to the one-sided torque. If the ratio of the local disk mass in planetesimals to planet mass is low, however, migration will stall. We quantify the boundaries separating the three accretion regimes.

• OSTI ID: 22086545
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 2 Vol. 758; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ASTRONOMY
ASTROPHYSICS
DENSITY
EXCITATION
GRAVITATIONAL INTERACTIONS
MASS
ORBITS
PLANETS
PROTOPLANETS
RECOILS
SATELLITES
SCATTERING
TORQUE