Spitzer View of Massive Star Formation in the Magellanic System
Remy Indebetouw, Erik Muller, Karl Gordon, Greg Sloan, You-Hua Chu, Robert Gruendl, Gerard Testor, and the SAGE-SMC team
Recent Spitzer mid-IR surveys reveal a large number of individually resolved massive young stellar objects (YSOs) in the Magellanic Clouds, providing an excellent opportunity to study massive star formation at metallicity and galactic environment different from the Galaxy. We have used Spitzer and complementary near-IR and optical data to study massive YSOs in HII complexes in the LMC and SMC and high N(HI) portion of Magellanic Bridge (Chen et al. 2009, 2010, 2011). We have modeled spectral energy distributions of YSOs and found their masses ranging 4−45 M¤ in the LMC/SMC, while 4−10 M¤ in the Bridge. To assess the environmental effects, we have estimated the instantaneous star formation efficiency (SFE) using complete lists of YSOs in the LMC and Bridge. We found that the LMC has ~3 times higher SFE than the Bridge, but the trend reverses at N(HI) < 1021 cm−2. This reverse is likely caused by different formation mechanisms of molecular clouds, such as colliding flows.