Astrophys. J., 854, 117-117 (2018/February-3)
Near-infrared stellar populations in the metal-poor, dwarf irregular galaxies Sextans A and Leo A.
JONES O.C., MACLAY M.T., BOYER M.L., MEIXNER M., McDONALD I. and MESKHIDZE H.
Abstract (from CDS):
We present JHKs 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 > 10–11M☉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)×10–9M☉yr–1 and (6.2±0.2)×10–7M☉yr–1, respectively. The majority of this dust is produced by a few very dusty evolved stars and does not vary strongly with metallicity.
© 2018. The American Astronomical Society. All rights reserved.
circumstellar matter - infrared: stars - stars: late-type - stars: mass-loss
VizieR on-line data:
<Available at CDS (J/ApJ/854/117): table1.dat table6.dat table9.dat>
Table 6: [JMB2018] LeoA NNN N=287 among (Nos 0-461), [JMB2018] SextansA NNN (Nos 0-491).
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