The relationship of dense gas to star formation in the Monoceros OB1 dark cloud

We have conducted a CS survey of the 10 outflows and 30 IRAS sources identified by Margulis, Lada, & Snell (1988) and Margulis, Lada, & Young (1989), in the Mon OB1 dark cloud to study the relationship between outflows, young stellar objects, and dense cores in this cloud. We detected the CS J = 2 → 1 transition in the vicinity of 20 of the 30 IRAS sources, six of which are associated with the six most massive outflows in this cloud. We did not detect CS emission toward the four remaining outflows; three of these outflows are not associated with IRAS sources. The brightest CS J = 2 → 1 emission is concentrated in two spatially extended regions encompassing five of the 10 outflows and eight of the IRAS sources. Within the extended regions, CS line widths are ∼30% broader near outflow lobes than on the line of sight toward IRAS sources. There is a strong correlation of CS antenna temperature with IRAS source luminosity and a weaker correlation of CS line width with IRAS source luminosity for IRAS sources associated with outflows in Mon OB1. There is no apparent correlation of either CS antenna temperature or line width with IRAS source luminosity for IRAS sources not associated with outflows (quiescent sources). We have detected the CS J = 5 → 4 transition in the vicinity of four outflow sources in this cloud and around none of the quiescent IRAS sources. The CS J = 5 → 4 emission is extended around the two most massive outflows in the cloud and has been mapped in these regions. CS J = 7 → 6 emission has been detected and mapped about the brightest outflow source in this cloud (Allen's star; Allen 1972). The J = 7 → 6 emission peaks at the position of the IRAS source. The morphology of the J = 7 → 6 emission differs from that of the J = 5 → 4 emission.