NEW CONSTRAINTS ON MASS-DEPENDENT DISRUPTION OF STAR CLUSTERS IN M51
- Department of Physics and Astronomy, The University of Toledo, Toledo, OH 43606 (United States)
- Space Telescope Science Institute, Baltimore, MD, 21218 (United States)
- Department of Astronomy, University of Massachusetts, Amherst, MA 01003 (United States)
- CICLOPS, Space Science Institute, 4750 Walnut Street, Boulder, CO 80301 (United States)
- Institute of Astronomy, Cambridge University, Cambridge (United Kingdom)
- Max-Planck-Institut fuer Astronomie, Koenigstuhl 17, D-69117 Heidelberg (Germany)
We use UBVI H{alpha} images of the Whirlpool galaxy, M51, taken with the Advanced Camera for Surveys and WFPC2 cameras on the Hubble Space Telescope (HST) to select star clusters, and to estimate their masses and ages by comparing their observed colors with predictions from population synthesis models. We construct the mass function of intermediate-age (1-4 x 10{sup 8} yr) clusters, and find that it is well described by a power law, {psi}(M) {proportional_to} M{sup {beta}}, with {beta} = -2.1 {+-} 0.2, for clusters more massive than M {approx} 6 x 10{sup 3} M{sub sun}. This extends the mass function of intermediate-age clusters in M51 to masses lower by nearly a factor of five over previous determinations. The mass function does not show evidence for curvature at either the high or low mass end. This shape indicates that there is no evidence for the earlier disruption of lower mass clusters compared with their higher mass counterparts (i.e., no mass-dependent disruption) over the observed range of masses and ages, or for a physical upper mass limit M{sub C} with which clusters in M51 can form. These conclusions differ from previous suggestions based on poorer-quality HST observations. We discuss their implications for the formation and disruption of the clusters. Ages of clusters in two 'feathers', stellar features extending from the outer portion of a spiral arm, show that the feather with a larger pitch angle formed earlier, and over a longer period, than the other.
- OSTI ID:
- 21567553
- Journal Information:
- Astrophysical Journal, Vol. 727, Issue 2; Other Information: DOI: 10.1088/0004-637X/727/2/88; ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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