Stellar populations of the dwarf irregular galaxy WLM

Journal Article · Tue Jul 01 04:00:00 EDT 1997 · Astronomical Journal

DOI:https://doi.org/10.1086/118461· OSTI ID:529978

Minniti, D; Zijlstra, A A ^[1]

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1. European Southern Observatory, Karl-Schwarzschild-Str. 2, D-85748 Garching b. Munchen (Germany)

We have obtained V-band photometry for 8000 stars, and I-band photometry for 16000 stars in the field of the dwarf irregular galaxy WLM, a member of the Local Group. From the VI color-magnitude diagram we infer metallicities and ages for the stellar populations in the main body and in the halo of WLM. The youngest stars in the galaxy have an age of {approximately}10{sup 7} Gyr. For the oldest stars we derive an age of {gt}10{sup 10} Gyr and a metallicity of [Fe/H]={minus}1.45{plus_minus}0.2. We construct a deep luminosity function, obtaining an accurate distance modulus m{minus}M=24.75{plus_minus}0.1 for this galaxy based on the I-magnitude of the RGB tip and adopting E(V{minus}I)=0.03. We establish the presence of an extended, slightly flattened halo consisting of Population II stars. Cluster D of Ables & Ables (1977, ApJS, 34, 245) is confirmed as the only globular cluster present in the main body of this galaxy. There are no other clusters brighter than I=19.5. The B{minus}V color gradient observed by Ables & Ables (1977) is shown to be caused by a stellar-population transition, and not a metallicity gradient or dust extinction. {copyright} {ital 1997 American Astronomical Society.}

• Research Organization: Lawrence Livermore National Laboratory
• DOE Contract Number: W-7405-ENG-48
• OSTI ID: 529978
• Journal Information: Astronomical Journal, Journal Name: Astronomical Journal Journal Issue: 1 Vol. 114; ISSN ANJOAA; ISSN 0004-6256
• Country of Publication: United States
• Language: English

Related Subjects

66 PHYSICS
AGE ESTIMATION
COLOR
COSMIC DUST
GALACTIC EVOLUTION
GALAXIES
GIANT STARS
LUMINOSITY
MORPHOLOGY
NEAR INFRARED RADIATION
PHOTOMETRY
STAR CLUSTERS
STARS
STELLAR RADIATION
VISIBLE RADIATION