Volume 416, Number 2, March III 2004
|Page(s)||537 - 553|
|Published online||27 February 2004|
European Southern Observatory (ESO), Karl-Schwarzschild-Str. 2, 85748 Garching b. München, Germany
Corresponding author: firstname.lastname@example.org
Accepted: 3 December 2003
A search for stellar clusters has been carried out in 18 nearby spiral galaxies, using archive images from the Wide Field Planetary Camera 2 on board the Hubble Space Telescope. All of the galaxies have previously been imaged from the ground in UBVI. A catalogue of structural parameters, photometry and comments based on visual inspection of the clusters is compiled and used to investigate correlations between cluster structure, environment, age and mass. Least-squares fits to the data suggest correlations between both the full-width at half-maximum (FWHM) and half-light radius () of the clusters and their masses (M) at about the level. Although both relations show a large scatter, the fits have substantially shallower slopes than for a constant-density relation (size ). However, many of the youngest clusters have extended halos which make the determinations uncertain. There is no evidence for galaxy-to-galaxy variations in the mean cluster sizes. In particular, the mean sizes do not appear to depend on the host galaxy star formation rate surface density. Many of the youngest objects (age years) are located in strongly crowded regions, and about 1/3–1/2 of them are double or multiple sources. The HST images are also used to check the nature of cluster candidates identified in a previous ground-based survey. The contamination rate in the ground-based sample is generally less than about 20%, but some cluster identifications remain ambiguous because of crowding even with HST imaging, especially for the youngest objects.
Key words: galaxies: star clusters / galaxies: spiral / catalogs
Full Tables [see full text]–[see full text], and [see full text] are only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (18.104.22.168) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/416/537
© ESO, 2004
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