Very high resolution radio observations of molecular cloud cores

In this thesis the environments of three young stellar objects are studied by means of molecular line and continuum observations. For each star forming region the distribution of gas has been traced from interstellar dimensions (∼ few pc) down to solar system sized condensations. Whilst the signposts of star formation are similar in each case, (i.e. the presence of OH and H2O masers, obscured infrared sources, broad CO lines, etc.), the source morphologies are quite different and exceedingly complex. The first region studied, G35.2-0.74N, contains probably the finest example of a rotating disc, seen almost edge on. In contrast, the dominant source of molecular line emission from G34.3+0.15 is a dense ultracompact core associated with a highly luminous HII region. Spectra observed towards this core show strong evidence of both self absorption and absorption against the continuum at velocities both red and blue shifted with respect to the cloud LSR velocity. The GGD12-15 molecular outflow resembles that of L1551, i.e. elongated red and blue shifted lobes. On closer inspection the flow is resolved into two components, one of which produces the L1551-like emission, the other highly chaotic. (author)