Spatially correlated cluster populations in the outer disk of ngc 3184

Stéphane Herbert-Fort, Dennis Zaritsky, John Moustakas, Daniel Christlein, Eric Wilcots, Andrea Baruffolo, Andrea Dipaola, Adriano Fontana, Emanuele Giallongo, Richard W. Pogge, Roberto Ragazzoni, Riccardo Smareglia

Research output: Contribution to journalArticlepeer-review

7 Scopus citations


We use deep (27.5 mag V-band point-source limiting magnitude) V- and U-band Large Binocular Telescope imaging to study the outer disk (beyond the optical radius R 25) of the non-interacting, face-on spiral galaxy NGC 3184 (D = 11.1 Mpc; R 25 = 11.1 kpc) and find that this outer disk contains >1000 objects (or marginally resolved "knots") resembling star clusters with masses 102-104 M and ages up to 1Gyr. We find statistically significant numbers of these cluster-like knots extending to 1.4 R 25, with the redder knots outnumbering bluer at the largest radii. We measure clustering among knots and find significant correlation to galactocentric radii of 1.5 R 25 for knot separations <1 kpc. The effective integrated surface brightness of this outer disk cluster population ranges from 30-32 mag arcsec-2 in V. We compare the H I extent to that of the correlated knots and find that the clusters extend at least to the damped Lyman-α threshold of H I column density (2 × 1020 cm-2; 1.62 R 25). The blue knots are correlated with H I spiral structure to 1.5 R 25, while the red knots may be correlated with the outer fringes of the H I disk to 1.7 R 25. These results suggest that outer disks are well populated, common, and long-lasting features of many nearby disk galaxies.

Original languageEnglish (US)
Pages (from-to)1977-1987
Number of pages11
JournalAstrophysical Journal
Issue number2
StatePublished - 2009


  • Galaxies: individual (NGC 3184)
  • Galaxies: star clusters
  • Galaxies: structure
  • Methods: statistical

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


Dive into the research topics of 'Spatially correlated cluster populations in the outer disk of ngc 3184'. Together they form a unique fingerprint.

Cite this