SURVEYING THE AGENTS OF GALAXY EVOLUTION IN THE TIDALLY STRIPPED, LOW METALLICITY SMALL MAGELLANIC CLOUD (SAGE-SMC). II. COOL EVOLVED STARS

By M. Boyer, S. Srinivasan, J. V. Loon, I. Mcdonald, M. Meixner, Dennis Zaritsky, K. Gordon, F. Kemper, B. Babler, M. Block and 10 more. 2011

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We investigate the infrared (IR) properties of cool, evolved stars in the Small Magellanic Cloud (SMC), including the red giant branch (RGB) stars and the dust-producing red supergiant (RSG) and asymptotic giant branch (AGB) stars using observations from the Spitzer Space Telescope Legacy program entitled “Surveying the Agents of Galaxy Evolution in the Tidally Stripped, Low Metallicity SMC,” or SAGE-SMC. The survey includes, for the first time, full spatial coverage of the SMC bar, wing, and tail regions at IR wavelengths (3.6–160 μm). We identify evolved stars using a combination of near-IR and mid-IR photometry and point out a new feature in the mid-IR color–magnitude diagram that may be due to particularly dusty O-rich AGB stars. We find that the RSG and AGB stars each contribute ≈20% of the global SMC flux (extended + point-source) at 3.6 μm, which emphasizes the importance of both stellar types to the integrated flux of distant metal-poor galaxies. The equivalent SAGE survey of the higher-metallicity Large Magellanic Cloud (SAGE-LMC) allows us to explore the influence of metallicity on dust production. We find that the SMC RSG stars are less likely to produce a large amount of dust (as indicated by the [3.6] − [8] color). There is a higher fraction of carbon-rich stars in the SMC, and these stars appear to reach colors as red as their LMC counterparts, indicating that C-rich dust forms efficiently in both galaxies. A preliminary estimate of the dust production in AGB and RSG stars reveals that the extreme C-rich AGB stars dominate the dust input in both galaxies, and that the O-rich stars may play a larger role in the LMC than in the SMC.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/351b337bce8097683c3e32d30d9836055b4d56b6

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Citations in the corpus

MESA ISOCHRONES AND STELLAR TRACKS (MIST). I. SOLAR-SCALED MODELS (2016, methodology): “Finally, although Boyer et al. (2011) took great care to ensure a high-fidelity sample, there is most likely a nonzero amount of contamination in the final sample of AGB stars by e.g., RSGs.”
SURVEYING THE AGENTS OF GALAXY EVOLUTION IN THE TIDALLY STRIPPED, LOW METALLICITY SMALL MAGELLANIC CLOUD (SAGE-SMC). I. OVERVIEW (2011, background): “, evolved stars (Boyer et al. 2011), young stellar objects (Sewílo et al. 2011, in prep.)”
A NEW GENERATION OF PARSEC-COLIBRI STELLAR ISOCHRONES INCLUDING THE TP-AGB PHASE (2017, background): “…of our dust growth model (Nanni et al. 2016) regards the production of carbon dust in circumstellar envelopes of C-stars, which are particularly relevant for the interpretation of the colors of the so-called extreme-AGB stars observed in infrared surveys of nearby galaxies (e.g. Boyer et al. 2011).”
The SAGE-Spec Spitzer Legacy Program: The Life Cycle of Dust and Gas in the Large Magellanic Cloud (2010, methodology): “The missing RSGs either have no 2MASS magnitudes or fall outside the (Boyer et al. 2011) colour cuts, with most (12) falling bluewards of the RSG cut shown in Fig.”