Astrophysics, abstract
astro-ph/0608325

From: Sijing Shen [view email]

Date: Tue, 15 Aug 2006 21:28:28 GMT (175kb)

Proto-Brown Dwarf Disks as Products of Protostellar Disk Encounters

Authors: Sijing Shen (1), James Wadsley (1) ((1) McMaster University)

Comments: 4 pages, 3 figures, accepted for publication in ApJ Letters

The formation of brown dwarfs via encounters between proto-stars has been confirmed with high-resolution numerical simulations with a restricted treatment of the thermal conditions. The new results indicate that young brown dwarfs (BDs) formed this way are disk-like and often reside in multiple systems. The newly-formed proto-BDs disks are up to 18 AU in size and spin rapidly making small-scale bipolar outflows, fragmentation and the possible formation of planetary companions likely as have recently been observed for BDs. The object masses range from 2 to 73 Jupiter masses, distributed in a manner consistent with the observed sub-stellar initial mass function. The simulations usually form multiple BDs on eccentric orbits about a star. One such system was hierarchical, a BD binary in orbit around a star, which may explain recently observed hierarchical systems. One third of the BDs were unbound after a few thousand years and interactions among orbiting BDs may eject more or add to the number of binaries. Improvements over prior work include resolution down to a Jupiter mass, self-consistent models of the vertical structure of the initial disks and careful attention to avoid artificial fragmentation.

http://arxiv.org/abs/astro-ph/0608325