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D.C. Jackson, E.D. Skillman, R.D. Gehrz, C.E. Woodward, E. Polomski (University of Minnesota)
Spitzer/IRAC observations at 3.6, 4.5, 5.8 and 8.0 \mum are presented along with publicly available broad- and narrow-band optical data to investigate the stellar populations and interstellar medium of the irregular galaxy WLM. These observations should provide a nearly complete census of the asymptotic giant branch stars. For the objects we assume to be AGB stars, we find at minimum 36% are not detected in the optical study. This is in addition to numerous objects optically classified as red giants, but which clearly have magnitudes and colors consistent with reddened AGBs. Using recently published models of mass-losing AGB stars (Groenewegen 2005), we are then able to estimate the total mass loss experienced by these reddened AGBs. Finally, we detect little if any diffuse 8.0 \mum emission, which would be indicative of hot (~350 K) dust or polycyclic aromatic hydrocarbon emission.
This work is supported in part by NASA (JPL/SSC 1256406, 1215746).
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Bulletin of the American Astronomical Society, 37 #4
© 2005. The American Astronomical Soceity.