Hubble space telescope photometry of globular clusters in M81

Julie B. Nantais, John P. Huchra, Andreas Zezas, Kosmas Gazeas, Jay Strader

Research output: Contribution to journalArticlepeer-review

16 Citations (Scopus)


We perform aperture photometry and profile fitting on 419 globular cluster (GC) candidates with mV ≤ 23mag identified in Hubble Space Telescope/Advanced Camera for Surveys BVI imaging, and estimate the effective radii of the clusters. We identify 85 previously known spectroscopically confirmed clusters, and newly identify 136 objects as good cluster candidates within the 3σ color and size ranges defined by the spectroscopically confirmed clusters, yielding a total of 221 probable GCs. The luminosity function peak for the 221 probable GCs with estimated total dereddening applied is V ∼(20.26 ± 0.13)mag, corresponding to a distance of ∼3.7 ± 0.3Mpc. The blue and red GC candidates, and the metal-rich and metal-poor spectroscopically confirmed clusters, respectively, are similar in half-light radius. Red confirmed clusters are about 6% larger in median half-light radius than blue confirmed clusters, and red and blue good GC candidates are nearly identical in half-light radius. The total population of confirmed and "good" candidates shows an increase in half-light radius as a function of galactocentric distance.

Original languageEnglish
Article number183
JournalAstronomical Journal
Issue number6
Publication statusPublished - Dec 2011


  • galaxies: individual (M81)
  • galaxies: spiral
  • galaxies: star clusters: general
  • galaxies: stellar content

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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