HII Regions, Embedded Protostars, and Starless Cores in Sharpless 2-157

Abstract

We present arcsecond resolution 1.4mm observations of the high mass star forming region, Sharpless 2-157, that reveal the cool dust associated with the first stages of star formation. These data are compared with archival images at optical, infrared, and radio wavelengths, and complemented with new arcsecond resolution mid-infrared data. We identify a dusty young HII region, numerous infrared sources within the cluster envelope, and four starless condensations. Three of the cores lie in a line to the south of the cluster peak, but the most massive one is right at the center and associated with a jumble of bright radio and infrared sources. This presents an interesting juxtaposition of high and low mass star formation within the same cluster which we compare with similar observations of other high mass star forming regions and discuss in the context of cluster formation theory.