Discovery of Extreme Carbon Stars in the Large Magellanic Cloud
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Using Spitzer IRAC and MIPS observations of the Large Magellanic Cloud, we have identified 13 objects that have extremely red mid-IR colors. Follow-up Spitzer IRS observations of seven of these sources reveal varying amounts of SiC and C2H2 absorption as well as the presence of a broad MgS feature in at least two cases, indicating that these are extreme carbon stars. Preliminary estimates find these objects have luminosities of (4-11) # 103 and L preliminary model fitting gives mass-loss rates between 4 # 10 5 and 2 # 10 4 M yr 1, higher than any known carbon- rich AGB star in the LMC. These spectral and physical properties require careful reconsideration of dust condensation and mass-loss processes for carbon stars in low-metallicity environments.
The Astrophysical Journal, 688: L9-L12, 2008 November 20