Boyer, ML, McQuinn, KBW, Barmby, P, Bonanos, AZ, Gehrz, RD, Gordon, KD, Groenewegen, MAT, Lagadec, E, Lennon, D, Marengo, M, McDonald, I, Meixner, M, Skillman, E, Sloan, GC, Sonneborn, G, van Loon, JT and Zijlstra, A (2015) An infrared census of dust in nearby galaxies with Spitxer (Dustings). II. Discovery of metal-poor dusty AGB stars. Astrophysical Journal, 800 (1). p. 51. ISSN 0004-637X

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The DUSTiNGS survey (DUST in Nearby Galaxies with Spitzer) is a 3.6 and 4.5 μm imaging survey of 50 nearby dwarf galaxies designed to identify dust-producing asymptotic giant branch (AGB) stars and massive stars. Using two epochs, spaced approximately six months apart, we identify a total of 526 dusty variable AGB stars (sometimes called "extreme" or x-AGB stars; [3.6]-[4.5] > 0.1 mag). Of these, 111 are in galaxies with [Fe/H] < –1.5 and 12 are in galaxies with [Fe/H] < –2.0, making them the most metal-poor dust-producing AGB stars known. We compare these identifications to those in the literature and find that most are newly discovered large-amplitude variables, with the exception of ≈30 stars in NGC 185 and NGC 147, 1 star in IC 1613, and 1 star in Phoenix. The chemical abundances of the x-AGB variables are unknown, but the low metallicities suggest that they are more likely to be carbon-rich than oxygen-rich and comparisons with existing optical and near-IR photometry confirm that 70 of the x-AGB variables are confirmed or likely carbon stars. We see an increase in the pulsation amplitude with increased dust production, supporting previous studies suggesting that dust production and pulsation are linked. We find no strong evidence linking dust production with metallicity, indicating that dust can form in very metal-poor environments.

Item Type: Article
Additional Information: ©IOP Publishing, American Astronomical Society
Uncontrolled Keywords: galaxies: dwarf, galaxies: stellar content, infrared: stars, Local Group, stars: AGB and post-AGB, stars: carbon
Subjects: Q Science > QB Astronomy
Q Science > QC Physics
Divisions: Faculty of Natural Sciences > School of Physical and Geographical Sciences
Related URLs:
Depositing User: Symplectic
Date Deposited: 14 Jul 2015 09:18
Last Modified: 07 May 2019 08:14

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