A HUBBLE SPACE TELESCOPE/WFPC2 SURVEY OF BRIGHT YOUNG CLUSTERS IN M31. III. STRUCTURAL PARAMETERS
- Department of Physics and Astronomy, University of Western Ontario, London, ON N6A 3K7 (Canada)
- INAF-Osservatorio Astronomico di Bologna, via Ranzani 1, 40127 Bologna (Italy)
- Palomar Observatory, Mail Stop 105-24, California Institute of Technology, Pasadena, CA 91125 (United States)
- Department of Astronomy, University of Washington, Seattle, WA 98195 (United States)
- Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138 (United States)
- European Southern Observatory, Karl-Schwarzschild-Strasse 2, 85748 Garching bei Muenchen (Germany)
Surface brightness profiles for 23 M31 star clusters were measured using images from the Wide Field Planetary Camera 2 on the Hubble Space Telescope, and fitted to two types of models to determine the clusters' structural properties. The clusters are primarily young ({approx}10{sup 8} yr) and massive ({approx}10{sup 4.5} M {sub sun}), with median half-light radius 7 pc and dissolution times of a few Gyr. The properties of the M31 clusters are comparable to those of clusters of similar age in the Magellanic Clouds. Simulated star clusters are used to derive a conversion from statistical measures of cluster size to half-light radius so that the extragalactic clusters can be compared to young massive clusters in the Milky Way. All three sets of star clusters fall approximately on the same age-size relation. The young M31 clusters are expected to dissolve within a few Gyr and will not survive to become old, globular clusters. However, they do appear to follow the same fundamental plane (FP) relations as old clusters; if confirmed with velocity dispersion measurements, this would be a strong indication that the star cluster FP reflects universal cluster formation conditions.
- OSTI ID:
- 21301508
- Journal Information:
- Astronomical Journal (New York, N.Y. Online), Journal Name: Astronomical Journal (New York, N.Y. Online) Journal Issue: 6 Vol. 138; ISSN 1538-3881
- Country of Publication:
- United States
- Language:
- English
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