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Hector Arce (Harvard University)
We use new millimeter wavelength observations to reveal the important effects that outflows from young stellar objects have on their surroundings. Our data samples the outflow-cloud interaction at different size scales, from the star-forming core to parsec-scale distances from the outflow source. By combining high sensitivity, and relatively high spatial resolution observations with large-scale maps at different molecular transitions, we are able to study the structure of the observed outflows, as well as the effects they have on the ambient gas. Using the FCRAO 14m telescope, we studied the effects that outflows have on their parent cores, by observing ---at high velocity resolution--- a sample of cores which harbor outflow sources. In order to study the outflow-cloud interaction on parsec scales, we observed two giant molecular outflows (PV Ceph and HH 300) and a large extent of their surroundings. These outflows were mapped in the 12CO(2--1) line, using the NRAO 12m telescope, and the 12CO(1--0) and 13CO(1--0) lines, using the FCRAO 14m telescope. We also performed high spatial and velocity resolution observations, with the IRAM 30m telescope, of the gas surrounding several HH knots of the PV Ceph flow.
We find that outflows, even from low-mass stars, can modify their host cloud's gas density and kinematical distribution at all the size scales we studied. With the two giant outflows data, we show how the gas spatial distribution, the velocity structure and the momentum distribution of both outflows lead us to conclude that they are predominantly formed by bow-shock prompt entrainment, from an episodic and precessing underlying wind. Our 13CO(1--0) observations show outflows are able to redistribute large amounts of their surrounding medium-density (n ~103 cm-3) gas. We conclude that the cumulative effect of many outflows have a strong influence on a molecular cloud's evolution and fate.
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The author(s) of this abstract have provided an email address for comments about the abstract: harce@cfa.harvard.edu