Discovery of Extreme Carbon Stars in the Large Magellanic Cloud
Abstract
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.
Citation
The Astrophysical Journal, 688: L9-L12, 2008 November 20