| Autor: |
Olivia C. Jones, Matthew T. Maclay, Martha L. Boyer, Margaret Meixner, Iain McDonald, Helen Meskhidze |
| Předmět: |
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| Zdroj: |
Astrophysical Journal; 2/20/2018, Vol. 854 Issue 2, p1-1, 1p |
| Abstrakt: |
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 , 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 and , respectively. The majority of this dust is produced by a few very dusty evolved stars and does not vary strongly with metallicity. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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