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S. J. Carey (Spitzer Science Center/Caltech), R. O. Redman (HIA/NRC-Canada), L. E. Allen (Harvard-Smithsonian CfA)
We present IRAC and MIPS data from 3.6 to 24 microns of three infrared-dark clouds (IRDC) identified in the MSX Galactic Plane Survey. Each cloud has significant extinction even at 24 microns. Initially, these objects were believed to be massive starless cores; however, the Spitzer data and complementary millimeter wave spectroscopy reveal that each IRDC is actively forming low to intermediate mass stars. Some of the embedded objects are only identified at 24 microns suggesting that they are early class 0 protostars. A census of the star forming content of each cloud will be presented. We will discuss the nature of the mid-infrared extinction towards these objects using estimates derived from the extinction of the diffuse infrared background towards these objects.
This work is based on observations made with the Spitzer Space Telescope, which is operated by the Jet Propulsion Laboratory, California Institute of Technology under NASA contract 1407. Support for this work was provided by NASA through contract 1256790 issued by JPL/Caltech.
The author(s) of this abstract have provided an email address for comments about the abstract: carey@ipac.caltech.edu
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Bulletin of the American Astronomical Society, 37 #2
© 2005. The American Astronomical Soceity.