A Dwarf Irregular Galaxy at the Edge of the Local Group: Stellar Populations and Distance of IC 5152
- Department of Physics, UMIST, P.O. Box 88, Manchester M60 1QD (United Kingdom)
- Lawrence Livermore National Laboratory, Institute of Geophysics and Planetary Phsyics, P.O. Box 808, Mail Stop L-413, Livermore, CA 94550 (United States)
We have obtained {ital V}- and {ital I}-band photometry for about 700 stars in the field of the dwarf irregular galaxy IC 5152, previously considered a possible member of the Local Group. Deep {ital VI} color-magnitude diagrams are presented of the main body of this galaxy and of a nearby field. We infer a distance by comparison with the {ital VI} color-magnitude diagrams of similar galaxies and with theoretical isochrones. The distance modulus to IC 5152 is found to be {ital m}thinsp{minus}thinsp{ital M}{sub 0}thinsp=thinsp26.15thinsp{plus_minus}thinsp0.2, adopting {ital E}({ital V}{minus}{ital I})thinsp=thinsp0. This distance of {ital D}thinsp=thinsp1.7 Mpc implies that IC 5152 is not a certain member of the Local Group. We also construct a deep optical luminosity function. By comparison with theoretical isochrones, we find a metallicity {ital Z}thinsp{approx}thinsp0.002, which is lower than previous estimates. Using this metallicity and distance, IC 5152 now fits the metallicity-luminosity relation for dwarf galaxies. The youngest stars in the field studied have an age of {approximately}10{sup 7} Gyr, and there is a substantial population of stars with logthinsp{ital t}thinsp{gt}thinsp7.8{endash}8 yr. The central region of IC 5152 is an active site of star formation, as found by comparing our optical photometry with {ital Hubble Space Telescope} ultraviolet images. Several candidate globular clusters are found, as well as a candidate for a potential nucleus. {copyright} {ital {copyright} 1999.} {ital The American Astronomical Society}
- OSTI ID:
- 698871
- Journal Information:
- Astronomical Journal, Journal Name: Astronomical Journal Journal Issue: 4 Vol. 117; ISSN ANJOAA; ISSN 0004-6256
- Country of Publication:
- United States
- Language:
- English
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