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Near-Infrared Stellar Populations in the metal-poor, Dwarf irregular Galaxies Sextans A and Leo A

Published online by Cambridge University Press:  30 December 2019

Olivia C. Jones Open the ORCID record for Olivia C. Jones [Opens in a new window] ,
Matthew T. Maclay ,
Martha L. Boyer ,
Margaret Meixner Open the ORCID record for Margaret Meixner [Opens in a new window]  and
Iain McDonald Open the ORCID record for Iain McDonald [Opens in a new window]
Olivia C. Jones
Affiliation:
UK Astronomy Technology Centre, Royal Observatory, Blackford Hill, Edinburgh, EH9 3HJ email: olivia.jones@stfc.ac.uk
Matthew T. Maclay
Affiliation:
Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA
Martha L. Boyer
Affiliation:
Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA
Margaret Meixner
Affiliation:
Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA
Iain McDonald
Affiliation:
Jodrell Bank Centre for Astrophysics, Alan Turing Building, The University of Manchester, Oxford Road, Manchester, M13 9PL, UK
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Abstract

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We present JHK observations of the metal-poor $$(\left[ {{\rm{Fe}}/{\rm{H}}} \right] < - 1.40)$$ dwarf-irregular galaxies, Leo A and Sextans A, obtained with the WIYN High-resolution Infrared Camera. Their near-IR stellar populations are characterized by using a combination of color-magnitude diagrams and by identifying long-period variable (LPV) stars. We detected red giant and asymptotic giant branch (AGB) stars, consistent with membership of the galaxy’s intermediate-age populations (2-8 Gyr old). We identify 32 dusty evolved stars in Leo A and 101 dusty stars in Sextans A, 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 majority of this dust is produced by a few very dusty evolved stars.

Keywords

stars: late-typeinfrared: starscircumstellar matterstars: mass-loss
Type
Contributed Papers
Information
Proceedings of the International Astronomical Union , Volume 14 , Symposium S343: Why Galaxies Care About AGB Stars: A Continuing Challenge through Cosmic Time , August 2018 , pp. 429 - 430
Copyright
© International Astronomical Union 2019 

References

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