Paper: astro-ph/0601013
Date: Sun, 1 Jan 2006 10:33:27 GMT (49kb)

Title: Dust Size Growth and Settling in a Protoplanetary Disk

Authors: Hideko Nomura and Yoshitsugu Nakagawa (Kobe University)

Comments: 27 pages, 8 figures, accepted for publication in the ApJ
\\
We have studied dust evolution in a quiescent or turbulent protoplanetary
disk by numerically solving coagulation equation for settling dust particles,
using the minimum mass solar nebular model. As a result, if we assume an
ideally quiescent disk, the dust particles settle toward the disk midplane to
form a gravitationally unstable layer within 2x10^3 - 4x10^4 yr at 1 - 30 AU,
which is in good agreement with an analytic calculation by Nakagawa, Sekiya, &
Hayashi (1986) although they did not take into account the particle size
distribution explicitly. In an opposite extreme case of a globally turbulent
disk, on the other hand, the dust particles fluctuate owing to turbulent motion
of the gas and most particles become large enough to move inward very rapidly
within 70 - 3x10^4 yr at 1 - 30 AU, depending on the strength of turbulence.

Our result suggests that global turbulent motion should cease for the
planetesimal formation in protoplanetary disks.

\\ ( http://arXiv.org/abs/astro-ph/0601013 , 49kb)