An HST-WFPC2 survey of bright young clusters in M31. IV. Ages and mass estimates - Astrophysics > Astrophysics of GalaxiesReportar como inadecuado




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Abstract: {Aims.} We present the main results of an imaging survey of possible youngmassive clusters YMC in M31 performed with the Wide Field and PlanetaryCamera2 WFPC2 on the Hubble Space Telescope HST. We present the images andcolor magnitude diagrams CMDs of all of our targets. {Methods.} Thereddening, age and, metallicity of the clusters were estimated by comparing theobserved CMDs and luminosity functions with theoretical models. Stellar masseswere estimated by comparison with theoretical models in the logAge vs.absolute integrated magnitude plane. {Results.} Nineteen of the twenty surveyedcandidates were confirmed to be real star clusters. Three of the clusters werefound not to be good YMC candidates from newly available integratedspectroscopy and were in fact found to be old from their CMD. Of the remainingsixteen clusters, fourteen have ages between 25 Myr and 280 Myr, two have olderages than 500 Myr lower limits. By including ten other YMC with HSTphotometry from the literature we have assembled a sample of 25 clustersyounger than 1 Gyr, with mass ranging from 0.6 x 10^4 M sun to 6 x 10^4 M sun,with an average of ~ 3 x 10^4 M sun. {Conclusions.} The clusters consideredhere are confirmed to have masses significantly higher than Galactic openclusters in the same age range. Our analysis indicates that YMCs are relativelycommon in all the largest star-forming galaxies of the Local Group.



Autor: S. Perina UniBO-OABO, J.G. Cohen CalTech, P. Barmby Univ. W. Ontario, M.A. Beasley UCO-Lick, M. Bellazzini INAF-OABO, J.P. Brodie

Fuente: https://arxiv.org/







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