Dense cores in dark clouds. VI - Shapes

Abstract

A comparison is presently conducted between 48 line-intensity maps of 16 dense cores in dark clouds, based on observations in the 13-mm line of NH3 and the 3-mm lines of CS and C(O-18). Core elongation in this sample does not differ significantly between cores with and without embedded stars; elongation appears to be a condition prior to star formation, rather than the consequence of formation. The characteristic elongation of dense cores implies that models of equilibrium between self-gravity and isotropic random motions are incomplete. The observed elongation of dense cores in projection is modeled as arising from a group of either prolate or oblate spheroids.