A Hubble Space Telescope census of nuclear star clusters in late-type spiral galaxies.: II.: Cluster sizes and structural parameter correlations

被引:179
作者
Böker, T
Sarzi, M
McLaughlin, DE
van der Marel, RP
Rix, HW
Ho, LC
Shields, JC
机构
[1] European Space Agcy, ESTEC, RSSD, Div Astrophys, NL-2200 AG Noordwijk, Netherlands
[2] Univ Oxford, Oxford OX1 3RH, England
[3] Space Telescope Sci Inst, Baltimore, MD 21218 USA
[4] Max Planck Inst Astron, D-69117 Heidelberg, Germany
[5] Observ Carnegie Inst Washington, Pasadena, CA 91101 USA
[6] Ohio Univ, Dept Phys & Astron, Clippinger Res Labs, Athens, OH 45701 USA
关键词
galaxies : nuclei; galaxies : spiral; galaxies : star clusters;
D O I
10.1086/380231
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
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 (r) over bar (e)=3.5 pc, with 50% of the sample falling in the range 2.4 pcless than or equal tor(e)less than or equal to5.0 pc. This narrow size distribution is statistically indistinguishable from that of Galactic globular clusters, even though the nuclear clusters are, on average, 4 mag brighter than the old globular clusters. 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.
引用
收藏
页码:105 / 118
页数:14
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