The spectral signatures of collapse and outflow around young stars

Abstract

Comparison of high angular resolution interferometric and lower resolution single-dish observations of NH 3 in molecular cloud cores around ultracompact H II regions suggests that the spectral line shapes observed at lower angular resolution may be used to determine the nature of the interaction between the newly formed stars, represented by the H II region, and the surrounding molecular gas. For example, VLA observations of NH 3 around NGC 7538-IRS 1 are reported. The single-dish observations show that the absorption lines which arise from gas in front of the H II region are blueshifted with respect to the emission which arise from the surrounding cloud.