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

TL;DR

This study provides a comprehensive infrared photometric catalog of 1750 massive stars in the Large Magellanic Cloud, revealing their infrared properties, dust presence, and emission characteristics, aiding interpretation of stellar populations in nearby galaxies.

Contribution

It offers the first extensive infrared catalog of massive stars in the LMC, analyzing their dust, emission, and spectral energy distributions with uniform photometry across multiple bands.

Findings

Supergiant B[e], red supergiant, and LBV stars are among the brightest infrared sources.

Infrared excesses due to free-free emission are detected in ~900 OB stars.

Dust is confirmed around 10 supergiant B[e] stars, with similar SED shapes.

Abstract

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 intrinsic 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.