CO Outflows from Young Stellar Objects

Abstract

We have mapped the CO J=1-0 emission from molecular outflows associatedwith six young stellar systems using the BIMA array. The systemsare all relatively nearby, have low-luminosity, and range from Class0 to Class II sources. The CO outflows in these systems are complicated,showing multipolar structures, multiple cavities, and asymmetriclobes. The complicated appearance of the CO outflows may result fromthe interactions between one or more outflows and the nonuniformambient cloud. The CO emission typically arises from shell structuresaround the outflow axis. For some outflows, there are also clumpyand bowlike structures in CO along the outflow axis within the shell.Comparing the observed outflow features to that of jet- and wind-drivenmodels, we find that the outflow systems show some features thatare characteristic of the jet-driven model and others characteristicof the wind-driven model. Simple models of jets or winds cannot reproducethe full range of kinematic features found in observed outflows.The jet-driven model requires jet wandering to produce the observedoutflow width and momentum content for most of these outflows, whilethe wind-driven model needs to have a collimated core with a strongvelocity gradient away from the core to produce the highly collimatedoutflows and the observed curved internal H$_{2}$ bow shock structures.