An updated catalog of M31 globular-like clusters: UBVRI photometry, ages, and masses

Zhou Fan*, Richard de Grijs, Xu Zhou

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

27 Citations (Scopus)


We present an updated UBVRI photometric catalog containing 970 objects in the field of M31, selected from the Revised Bologna Catalog (RBC v.4.0), including 965, 967, 965, 953, and 827 sources in the individual UBVRI bands, respectively, of which 205, 123, 14, 126, and 109 objects do not have previously published photometry. Photometry is performed using archival images from the Local Group Galaxies Survey, which covers 2.2 deg2 along the major axis of M31. Detailed comparisons show that our photometry is fully consistent with previous measurements in all filters. We focus on 445 confirmed "globular-like" clusters and candidates, comprising typical globular and young massive clusters. The ages and masses of these objects are derived by comparing their observed spectral-energy distributions with simple stellar population synthesis. Approximately half of the clusters are younger than 2 Gyr, suggesting that there has been significant recent active star formation in M31, which is consistent with previous results. We note that clusters in the halo (rprojected > 30 kpc) are composed of two different components: older clusters with ages >10 Gyr and younger clusters with ages around 1 Gyr. The spatial distributions show that the young clusters (<2 Gyr) are spatially coincident with the galaxy's disk, including the "10 kpc ring," the "outer ring," and the halo of M31, while the old clusters (>2 Gyr) are spatially correlated with the bulge and halo. We also estimate the masses of the 445 confirmed clusters and candidates in M31 and find that our estimates agree well with previously published values. We find that none of the young disk clusters can survive the inevitable encounters with giant molecular clouds in the galaxy's disk and that they will eventually be disrupted on timescales of a few Gyr. Specifically, young disk clusters with a mass of 10M are expected to dissolve within 3.0 Gyr and will, thus, not evolve to become globular clusters.

Original languageEnglish
Pages (from-to)200-213
Number of pages14
JournalAstrophysical Journal
Issue number1
Publication statusPublished - 10 Dec 2010
Externally publishedYes


  • catalogs
  • galaxies: individual (M31)
  • galaxies: star clusters: general
  • globular clusters: general


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