Paper: astro-ph/0601094
Date: Thu, 5 Jan 2006 03:34:52 GMT (296kb)

Title: High-Resolution Simulations of a Moon-Forming Impact and Post-Impact
Evolution

Authors: Keiichi Wada (1), Eiichiro Kokubo (1) and Junichiro Makino (2) ((1)
National Astronomical Observatory of Japan, (2) University of Tokyo)

Comments: ApJ 638, Feb. 20 in press
\\
In order to examine the ``giant impact hypothesis'' for the Moon formation,
we run the first grid-based, high-resolution hydrodynamic simulations for an
impact between proto-Earth and a proto-planet. The spatial resolution for the
impact-generated disk is greatly improved from previous particle-based
simulations. This allows us to explore fine structures of a circumterrestrial
debris disk and its long-term evolution. We find that in order to form a debris
disk from which a lunar-sized satellite can be accumulated, the impact must
result in a disk of mostly liquid or solid debris, where pressure is not
effective, well before the accumulation process starts. If the debris is
dominated by vapor gas, strong spiral shocks are generated, and therefore the
circumterrestrial disk cannot survive more than several days. This suggests
that there could be an appropriate mass range for terrestrial planets to harbor
a large moon as a result of giant impacts, since vaporization during an impact
depends on the impact energy.

\\ ( http://arXiv.org/abs/astro-ph/0601094 , 296kb)