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Date and Time of the Query: 2019-05-23 T16:11:08 PDT
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For refcode 2018ApJ...854..117J:
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Copyright by American Astronomical Society. Reproduced by permission
2018ApJ...854..117J Near-infrared Stellar Populations in the Metal-poor, Dwarf Irregular Galaxies Sextans A and Leo A Jones, Olivia C.; Maclay, Matthew T.; Boyer, Martha L.; Meixner, Margaret; McDonald, Iain; Meskhidze, Helen Abstract. We present JHK_ s_ observations of the metal-poor ([Fe/H] < -1.40) dwarf-irregular galaxies, Leo A and Sextans A, obtained with the WIYN High-resolution Infrared Camera at Kitt Peak. Their near-IR stellar populations are characterized by using a combination of color--magnitude diagrams and by identifying long-period variable stars. We detected red giant and asymptotic giant branch stars, consistent with membership of the galaxy's intermediate-age populations (2--8 Gyr old). Matching our data to broadband optical and mid-IR photometry, we determine luminosities, temperatures, and dust-production rates (DPR) for each star. We identify 32 stars in Leo A and 101 stars in Sextans A with a DPR > {10}^-11^ {M}_o_ {yr}}^-1^, confirming that metal-poor stars can form substantial amounts of dust. We also find tentative evidence for oxygen-rich dust formation at low metallicity, contradicting previous models that suggest oxygen-rich dust production is inhibited in metal-poor environments. The total rates of dust injection into the interstellar medium of Leo A and Sextans A are (8.2+/- 1.8)x {10}^-9^ {M}_o_ {yr}}^-1^ and (6.2+/- 0.2)x {10}^-7^ {M}_o_ {yr}}^-1^, respectively. The majority of this dust is produced by a few very dusty evolved stars and does not vary strongly with metallicity. Key words: circumstellar matter, infrared: stars, stars: late-type, stars: mass-loss
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