The LMC’s Top 250: Classification of the Most Luminous Compact 8 µm Sources in the Large Magellanic Cloud

To ascertain the nature of the brightest compact mid-infrared sources in the Large Magellanic Cloud (LMC), we have applied an updated version of the Buchanan et al. (2006) 2MASS-MSX color classification system, which is based on the results of Spitzer Space Telescope spectroscopy, to a mid-infrared (8 µm) flux-limited sample of 250 LMC objects for which 2MASS and MSX photometry is available. The resulting 2MASS-MSX (“JHK8”) color-based classifications of these sources, which constitute the most mid-IR-luminous objects in the LMC, were augmented, cross-checked, and corrected where necessary via a variety of independent means, such that only 47 sources retain tentative classifications and only 10 sources cannot be classified at all. The sample is found to consist primarily of carbon-rich asymptotic giant branch (AGB) stars (� 35%), red supergiants (�18%), and compact H ii regions (� 30%), with additional, small populations of oxygen-rich AGB stars (� 4%), dusty, early-type emission-line stars (� 3%), and foreground, O-rich AGB stars in the Milky Way (� 3%). The very large ratio of C-rich to O-rich objects among the luminous and heavily dust-enshrouded AGB stars in our LMC IR source sample is consistent with the hypothesis that