AAS 205th Meeting, 9-13 January 2005
Session 140 Cold Gas and Molecular Clouds
Poster, Thursday, January 13, 2005, 9:20am-4:00pm, Exhibit Hall

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[140.07] 12CO and 13CO J=2-1 Maps of the Sh254-258 Molecular Cloud

K. Schlottman, J. Bieging, B. Vila Vilaro, W. Peters (Steward Observatory, University of Arizona)

We present maps of 12CO and 13CO J=2-1 emission from the molecular clouds associated with the Sharpless 254-258 H II region complex. The observations were made with the University of Arizona's Heinrich Hertz Telescope on Mt. Graham, AZ, using full spatial sampling to give a resolution of 32 arcseconds, and an rms sensitivity of 0.25 K-TA* per 1.3 km/s velocity channel. We use the line intensities of the two isotopomers to constrain an LVG model for the temperature, density, and total column density of the resolved cloud cores and other regions of interest.

The brightest molecular cloud cores are characterized by moderately warm (>30 K) temperatures and high densities (>104 H2 cm-3). We compare our maps with previous CO J=1-0 maps by Carpenter et al. (1995) and with optical, radio continuum, and mid-IR images of this region. There are striking correlations in morphology between the warm dense CO cores and strong thermal dust emission. The shape of the molecular clouds compared with the distribution of the ionized gas suggests that the entire cloud complex has undergone a series of episodes of massive star formation, possibly in a sequence triggered by the effects of H II region expansion and stellar winds.

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© 2004. The American Astronomical Society.