March 18, 1999 CfA Colloquium

Title: The Formation of Low Mass Stars in Small Clusters

Speaker: William J. Welch

Abstract: The formation of low mass stars in their earliest stages is obscured in the visible by the dust of surrounding molecular clouds. The process is best observed at long wavelengths where the emission of dust continuum and molecular lines from the compact stellar envelopes can escape the clouds and be detected. We discuss millimeter wavelength observations of a number of star forming cores which correspond to point sources in the IRAS survey. The angular resolution is adequate to reveal compact disks as well as more extended envelopes. Most striking is the fact that in each of the dozen cores studied there are multiple stars forming. Although fragmentation of a single centrally condensed protostellar envelope is a possible description of the dynamics of each core, the structures are more consistent with the idea that the separate stars come from sub-cores that formed as part of the overall core. Models of the envelope emission around separate stars suggest that the envelopes may be infalling and give timescales for the formation.

Reference for students: Shu, F. 1977, ApJ, 214, 488. Lunch on Friday, 12:30, A-101