Anomalous Stellar Populations in Low-surface-brightness Galaxies

Journal Article · Mon Feb 01 04:00:00 EST 2021 · The Astronomical Journal (Online)

DOI:https://doi.org/10.3847/1538-3881/ABD54D· OSTI ID:23159120

Schombert, James ^[1]; McGaugh, Stacy ^[2]

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1. Institute for Fundamental Science, University of Oregon, Eugene, OR 97403 (United States)
2. Department of Astronomy, Case Western Reserve University, Cleveland, OH 44106 (United States)

We present new Hubble Space Telescope WFC3 near-IR observations of the color–magnitude diagrams (CMDs) in two low-surface-brightness galaxies, F575-3 and F615-1, notable for having no current star formation based on a lack of Hα emission. Key features of the near-IR CMDs are resolved, such as the red giant branch (RGB), the asymptotic giant branch (AGB) region, and the top of the blue main sequence. F575-3 has the bluest RGB of any CMD in the literature, indicating an extremely low mean metallicity. F615-1 has unusually wide RGB and AGB sequences, suggesting multiple episodes of star formation from metal-poor gas, and possibly infalling material. Both galaxies have an unusual population of stars to the red of the RGB and lower in luminosity than typical AGB stars. These stars have normal optical colors but abnormal near-IR colors. We suggest that this population of stars might be analogous to local peculiar stars like Be stars with strong near-IR excesses owing to a surrounding disk of hot gas.

• OSTI ID: 23159120
• Journal Information: The Astronomical Journal (Online), Journal Name: The Astronomical Journal (Online) Journal Issue: 2 Vol. 161; ISSN 1538-3881
• Country of Publication: United States
• Language: English

Related Subjects

47 OTHER INSTRUMENTATION
79 ASTRONOMY AND ASTROPHYSICS
ASYMPTOTIC SOLUTIONS
BRIGHTNESS
EMISSION
GALAXIES
LUMINOSITY
METALLICITY
METALS
STARS
SURFACES
TELESCOPES