Infrared properties of Active OB stars in the Magellanic Clouds from the Spitzer SAGE Survey

摘要

We present a study of the infrared properties of 4922 spectroscopicallyconfirmed massive stars in the Large and Small Magellanic Clouds, focusing onthe active OB star population. Besides OB stars, our sample includes yellow andred supergiants, Wolf-Rayet stars, Luminous Blue Variables (LBVs) andsupergiant B[e] stars. We detect a distinct Be star sequence, displaced to thered, and find a higher fraction of Oe and Be stars among O and early-B stars inthe SMC, respectively, when compared to the LMC, and that the SMC Be starsoccur at higher luminosities. We also find photometric variability among theactive OB population and evidence for transitions of Be stars to B stars andvice versa. We furthermore confirm the presence of dust around all thesupergiant B[e] stars in our sample, finding the shape of their spectral energydistributions (SEDs) to be very similar, in contrast to the variety of SEDshapes among the spectrally variable LBVs.