ar X iv : a st ro - p h / 07 03 51 0 v 1 1 9 M ar 2 00 7 Multi - object Spectroscopy of Young Star Clusters in NGC 4676
نویسندگان
چکیده
Galaxy interactions are known to trigger starbursts. The young star clusters formed in mergers may be young globular clusters. The ages of these young star clusters yield the timing of interaction-triggered star formation and provide an important way to reconstruct the history of merging galaxies. Here we present the first results from our investigation into age and metallicity of twelve young clusters in the merging galaxy pair NGC4676, using spectra from the multiobject Low Resolution Imaging Spectrometer (LRIS) on Keck. For ten clusters, comparison of the Balmer emission lines with model equivalent widths (EWs) yields ages less than 10Myr. Two spectra display Balmer absorption lines typical of star clusters dominated by A-type stars, with estimated ages of about 170Myr. These ages are comparable to the dynamical age of the tidal tails and are consistent with star formation triggered during the first passage of the pair. The locations of these two clusters in the tidal tails are generally consistent with predictions of shockinduced star formation models. One of these older objects appears unresolved on the image and is luminous enough to qualify as a young globular cluster. Using EWs of the diagnostic lines [O II] and [O III], we obtain oxygen abundances in the range 7.3 < 12 + log(O/H) < 9.0. These values show a nearly flat distribution along the northern tail, suggesting efficient gas mixing in the tail. Subject headings: galaxies: star clusters — galaxies: individual(NGC4676) — galaxies: abundances — galaxies: interactions
منابع مشابه
ar X iv : a st ro - p h / 07 03 51 0 v 2 2 2 M ar 2 00 7 Multi - object Spectroscopy of Young Star Clusters in NGC 4676
Galaxy interactions are known to trigger starbursts. The young star clusters formed in mergers may be young globular clusters. The ages of these young star clusters yield the timing of interaction-triggered star formation and provide an important way to reconstruct the history of merging galaxies. Here we present the first results from our investigation into age and metallicity of twelve young ...
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