Spitzer SAGE Infrared Photometry of Massive Stars in the Large Magellanic Cloud

A. Z. Bonanos (1,2), D. L. Massa (2), M. Sewilo (2), D. J. Lennon (2), N. Panagia (2,3), L. J. Smith (2), M. Meixner (2), B. L. Babler (4), S. Bracker (4), M.R. Meade (4), K.D. Gordon (2), J. L. Hora (5), R. Indebetouw (6), B. A. Whitney (7)

1 - Giacconi Fellow
2 - Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA
3 - INAF/Osservatorio Astrofisico di Catania, Via S.Sofia 78, I-95123 Catania, Italy; and Supernova Ltd.,
VGV #131, Northsound Road, Virgin Gorda, British Virgin Islands
4 - Department of Astronomy, 475 North Charter St., University of Wisconsin, Madison, WI 53706, USA
5 - Harvard-Smithsonian Center for Astrophysics, 60 Garden St., MS 67, Cambridge, MA 02138, USA
6 - Department of Astronomy, University of Virginia, PO Box 3818, Charlottesville, VA 22903, USA
7 - Space Science Institute, 4750 Walnut St., Suite 205, Boulder, CO 80301, USA

We present a catalog of 1750 massive stars in the Large Magellanic Cloud, with accurate spectral types compiled from the literature, and a photometric catalog for a subset of 1268 of these stars, with the goal of exploring their infrared properties. The photometric catalog consists of stars with infrared counterparts in the Spitzer SAGE survey database, for which we present uniform photometry from 0.3-24 microns in the UBVIJHKs+IRAC+MIPS24 bands. The resulting infrared color-magnitude diagrams illustrate that the supergiant B[e], red supergiant and luminous blue variable (LBV) stars are among the brightest infrared point sources in the Large Magellanic Cloud, due to their instrinsic brightness, and at longer wavelengths, due to dust. We detect infrared excesses due to free-free emission among ~900 OB stars, which correlate with luminosity class. We confirm the presence of dust around 10 supergiant B[e] stars, finding the shape of their spectral energy distributions (SEDs) to be very similar, in contrast to the variety of SED shapes among the spectrally variable LBVs. The similar luminosities of B[e] supergiants (log L/Lo>=4) and the rare, dusty progenitors of the new class of optical transients (e.g. SN 2008S and NGC 300 OT), plus the fact that dust is present in both types of objects, suggests a common origin for them. We find the infrared colors for Wolf-Rayet stars to be independent of spectral type and their SEDs to be flatter than what models predict. The results of this study provide the first comprehensive roadmap for interpreting luminous, massive, resolved stellar populations in nearby galaxies at infrared wavelengths.

Reference: The Astronomical Journal
Status: Manuscript has been accepted

Weblink: http://arxiv.org/abs/0905.1328v2


Email: bonanos@stsci.edu