University of Hertfordshire

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  • 901282

    Accepted author manuscript, 357 KB, PDF document

  • T. Baker
  • M. Sarzi
  • D.E. McLaughlin
  • R. van der Marel
  • H-W. Rix
  • L. Ho
  • J.C. Shields
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Original languageEnglish
Pages (from-to)105-118
JournalAstronomical Journal
Journal publication date2004
Volume127
Issue1
Publication statusPublished - 2004

Abstract

We investigate the structural properties of nuclear star clusters in late-type spiral
galaxies. More specifically, we fit analytical models to Hubble Space Telescope images of 39 nuclear clusters in order to determine their effective radii after correction for the instrumental point spread function. We use the results of this analysis to compare the luminosities and sizes of nuclear star clusters to those of other ellipsoidal stellar systems, in particular the Milky Way globular clusters. Our nuclear clusters have a median effective radius of re?? = 3.5 pc, with 50% of the sample falling between 2.4 pc ≤ re ≤ 5.0 pc. This narrow size distribution is statistically indistinguishable from that of Galactic globular clusters, even though the nuclear clusters are on average 4 magnitudes brighter than the old globulars. We discuss some possible interpretations of this result.
From a comparison of nuclear cluster luminosities with various properties of their host galaxies, we confirm that more luminous galaxies harbor more luminous nuclear clusters.
It remains unclear whether this correlation mainly reflects the influence of galaxy size, mass, and/or star formation rate. Since the brighter galaxies in our sample typically have stellar disks with a higher central surface brightness, nuclear cluster luminosity also correlates with this property of their hosts. On the other hand, we find no evidence for a correlation between the presence of a nuclear star cluster and the presence of a large-scale stellar bar.

ID: 182088