The Spitzer Survey of the Small Magellanic Cloud: S3MC Imaging and Photometry in the Mid- and Far-Infrared Wave Bands

A.D. Bolatto, J.D. Simon, S. Stanimirovic, J. Van Loon, R.Y. Shah, K. Venn, A.K. Leroy, K. Sandstrom, J.M. Jackson, F.P. Israel, A. Li, Lister Staveley-Smith, C. Bot, F. Boulanger, M. Rubio

    Research output: Contribution to journalArticle

    159 Citations (Scopus)

    Abstract

    We present the initial results from the Spitzer Survey of the Small Magellanic Cloud (S3MC), which imaged the star-forming body of the SMC in all seven MIPS and IRAC wave bands. We find that the F8/F24 ratio (an estimate of PAH abundance) has large spatial variations and takes a wide range of values that are unrelated to metallicity but anticorrelated with 24 μm brightness and F24/F70 ratio. This suggests that photodestruction is primarily responsible for the low abundance of PAHs observed in star-forming low-metallicity galaxies. We use the S3MC images to compile a photometric catalog of ~400,000 mid- and far-infrared point sources in the SMC. The sources detected at the longest wavelengths fall into four main categories: (1) bright 5.8 μm sources with very faint optical counterparts and very red mid-infrared colors ([5.8] - [8.0] > 1.2), which we identify as YSOs; (2) bright mid-infrared sources with mildly red colors (0.16 lesssim [5.8] - [8.0] <0.6), identified as carbon stars; (3) bright mid-infrared sources with neutral colors and bright optical counterparts, corresponding to oxygen-rich evolved stars; and (4) unreddened early B stars (B3-O9) with a large 24 μm excess. This excess is reminiscent of debris disks and is detected in only a small fraction of these stars (lesssim5%). The majority of the brightest infrared point sources in the SMC fall into groups 1-3. We use this photometric information to produce a catalog of 282 bright YSOs in the SMC with a very low level of contamination (~7%).
    Original languageEnglish
    Pages (from-to)212-232
    JournalThe Astrophysical Journal
    Volume655
    Issue number1
    DOIs
    Publication statusPublished - 2007

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