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Session 21 - Jets, H-H Objects, and Molecular Outflows.
Display session, Monday, January 15
North Banquet Hall, Convention Center

[21.14] Spectroscopic Evidence of Infall and Outflow Around Intermediate/High-Mass YSOs in the Mon OB1 Dark Cloud

G. A. Wolf-Chase (NASA Ames)

We present multitransitional CS and CO observations toward two Class I intermediate/high-mass IRAS sources which are driving outflows in the southern portion of the Mon OB1 dark cloud. C^18O observations, as well as comparison of the masses and sizes of the associated outflows, indicate an approximate r^-2 density distribution in the extended cores associated with these objects. The outflows dominate the kinematic structure of the CS J=2\rightarrow1, J=3\rightarrow2, and J=5\rightarrow4 spectra. Toward the sources, line centroid velocities get redder with increasing optical depth. Line centroid velocities of spectra taken at positions along the outflow axes shift in the same sense as the outflows. Perpendicular to the outflow axes, line centroid velocities get redder as positions approach the sources. However, CS J=7\rightarrow6 spectra around NGC 2264 IRS show the signature of infall over a region of at least 0.1 pc perpendicular to the direction of the outflow. Line peaks and centroid velocities get bluer approaching the source in this direction. The CS J=7\rightarrow6 centroid velocity is also blueshifted relative to the CS J=2\rightarrow1, J=3\rightarrow2, and J=5\rightarrow4 centroid velocities toward NGC 2264 IRS. No CS J=7\rightarrow6 emission was detected toward the other source. In both sources, integrated intensity contours of the CS J=5\rightarrow4 emission are extended in the direction of the outflows. However, the CS J=7\rightarrow6 emission toward NGC 2264 IRS is extended in the direction perpendicular to the outflow. We discuss the implications of extending the theoretical picture developed for infall around low-mass stars to this source.

Program listing for Monday