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An HST/WFPC Survey of Bright Young Clusters in M31. II. Photometry of Less Luminous Clusters in the Fields

Hodge, P. W. and Krienke, O. K. and Bellazzini, M. and Perina, S. and Barmby, P. and Cohen, J. G. and Puzia, T. H. and Strader, J. (2009) An HST/WFPC Survey of Bright Young Clusters in M31. II. Photometry of Less Luminous Clusters in the Fields. Astronomical Journal, 138 (3). pp. 770-779. ISSN 0004-6256.

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We report on the properties of 89 low-mass star clusters located in the vicinity of luminous young clusters ("blue globulars") in the disk of M31. Eighty-two of the clusters are newly detected. We have determined their integrated magnitudes and colors, based on a series of Hubble Space Telescope (HST)/Wide Field Planetary Camera 2 exposures in blue and red (HST filters F450W and F814W). The integrated apparent magnitudes range from F450W = 17.5 to 22.5, and the colors indicate a wide range of ages. Stellar color-magnitude diagrams for all clusters were obtained and those with bright enough stars were fit to theoretical isochrones to provide age estimates. The ages range from 12 Myr to >500 Myr. Reddenings, which average E(F450 – F814) = 0.59 with a dispersion of 0.21 mag, were derived from the main-sequence fitting for those clusters. Comparison of these ages and integrated colors with single population theoretical models with solar abundances suggests a color offset of 0.085 mag at the ages tested. Estimated ages for the remaining clusters are based on their measured colors. The age-frequency diagram shows a steep decline of number with age, with a large decrease in number per age interval between the youngest and the oldest clusters detected.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Bellazzini, M.0000-0001-8200-810X
Barmby, P.0000-0003-2767-0090
Cohen, J. G.0000-0002-8039-4673
Puzia, T. H.0000-0003-0350-7061
Strader, J.0000-0002-1468-9668
Additional Information:© 2009. The American Astronomical Society. Received 2009 April 9; accepted 2009 June 26; published 2009 July 24. This paper was based on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Institute, which is operated by the Association of Universities for Research in Astronomy, Inc. under NASA contract NAS 5-26555. These observations are associated with program GOI-10818 (PI: J. G. Cohen) and were partially funded under that program.
Funding AgencyGrant Number
Subject Keywords:galaxies: individual (NGC 224, M31, Andromeda); galaxies: star clusters; galaxies: stellar content; Local Group
Issue or Number:3
Record Number:CaltechAUTHORS:20090916-112836481
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Official Citation:An HST/WFPC Survey of Bright Young Clusters in M31. II. Photometry of Less Luminous Clusters in the Fields P. W. Hodge, O. K. Krienke, M. Bellazzini, S. Perina, P. Barmby, J. G. Cohen, T. H. Puzia, and J. Strader 2009 The Astronomical Journal 138 770-779 doi: 10.1088/0004-6256/138/3/770
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:15880
Deposited By: Ruth Sustaita
Deposited On:16 Sep 2009 20:24
Last Modified:10 Dec 2019 22:33

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