Millimeter observation of low mass star formation in rho Ophiuchus A and B1

This thesis presents evidence for time-dependent sulfur chemistry in the Ophiuchus star formation complex. The focus is on a 15{dollar}spprime{dollar} x 15{dollar}spprime{dollar} area centered at {dollar}alpha (J2000) = 16sp{lcub}h{rcub}26sp{lcub}m{rcub}46sbsp{lcub}.{rcub}{lcub}s{rcub}17{dollar} and {dollar}delta (J2000) = {lcub}-{rcub}24spcirc 28spprime 58{lcub}buildrel{lcub}primeprime{rcub}over{lcub}.{rcub}{rcub}62,{dollar} which encompasses the molecular core Oph B1 and the VLA 1623 outflow region. I discuss millimeter spectral line observations carried out with the Berkeley-Illinois-Maryland Association (BIMA) interferometer and National Radio Astronomy Observatory (NRAO) 12m telescope.; A multi-transition SO and CO analysis establishes that there is an SO "plume" at Oph B1. The SO fractional abundance there is enhanced by more than an order of magnitude compared to quiescent dense cores. It is furthermore shown that 2408.6-2229, a sub-stellar Class III YSO {dollar}({lcub}sim{rcub}1 times 10sp6{dollar} yrs), is embedded in a thin sheet of cold dense gas. This morphology suggests compression, perhaps by energetic events in the background Scorpius-Centaurus OB2 association. The enhanced SO abundance at Oph B1 could be interpreted as a relic of shock induced star formation.; The neighboring VLA 1623 belongs to Class 0 {dollar}({lcub}sim{rcub}1 times 10sp4{dollar} yrs) and is considerably less evolved than the Oph B1 Class III source. It is demonstrated that another high density tracer, {dollar}rm Hsp{lcub}13{rcub}COsp+,{dollar} has comparable abundances both here and at Oph B1. However in striking contrast to Oph B1, there is no observable SO abundance enhancement. Comparison between the two regions offers compelling evidence for time-dependent sulfur chemistry. Whereas shock activity may have played a role in Oph B1, the SO "plume" may also simply be a result of the greater time available for chemical processing.