Open AccessA Young Stellar Cluster in the Nucleus of NGC 4449
Author(s) -
Torsten Böker,
Roeland P. van der Marel,
Lisa M. Mazzuca,
Hans-Walter Rix,
Gregory Rudnick,
Luis C. Ho,
Joseph C. Shields
Publication year - 2001
Publication title -
the astronomical journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.61
H-Index - 271
eISSN - 1538-3881
pISSN - 0004-6256
DOI - 10.1086/319415
Subject(s) - metallicity , physics , astrophysics , balmer series , stellar population , star cluster , galaxy , population , cluster (spacecraft) , astronomy , spectral line , star formation , emission spectrum , demography , sociology , computer science , programming language
We have obtained 1-2 A resolution optical Echellette spectra of the nuclearstar cluster in the nearby starburst galaxy NGC 4449. The light is clearlydominated by a very young (6-10 Myr) population of stars. For our age dating,we have used recent population synthesis models to interpret the observedequivalent width of stellar absorption features such as the HI Balmer seriesand the CaII triplet around 8500 A. We also compare the observed spectrum ofthe nuclear cluster to synthesized spectra of simple stellar populations ofvarying ages. All these approaches yield a consistent cluster age. Metallicityestimates based on the relative intensities of various ionization lines yieldno evidence for significant enrichment in the center of this low mass galaxy:the metallicity of the nuclear cluster is about one fourth of the solar value,in agreement with independent estimates for the disk material of NGC 4449.Comment: 24 pages (incl. 7 figures), accepted by AJ, March 2001 issue revised version with minor changes and additions, one additional figur
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