OLD MASSIVE GLOBULAR CLUSTERS AND THE STELLAR HALO OF THE DWARF STARBURST GALAXY NGC 4449

Journal Article · Wed Feb 15 04:00:00 EST 2012 · Astronomical Journal (New York, N.Y. Online)

DOI:https://doi.org/10.1088/0004-6256/143/2/52· OSTI ID:22034708

Strader, Jay; Seth, Anil C; Caldwell, Nelson ^[1]

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1. Department of Physics and Astronomy, Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138 (United States)

We use Hubble Space Telescope imaging to show that the nearby dwarf starburst galaxy NGC 4449 has an unusual abundance of luminous red star clusters. Joint constraints from integrated photometry, low-resolution spectroscopy, dynamical mass-to-light ratios, and resolved color-magnitude diagrams provide evidence that some of these clusters are old globular clusters (GCs). Spectroscopic data for two massive clusters suggest intermediate metallicities ([Fe/H] {approx}-1) and subsolar Mg enhancement ([Mg/Fe] {approx}-0.1 to -0.2). One of these clusters may be the nucleus of a tidally disrupting dwarf galaxy; the other is very massive ({approx}3 Multiplication-Sign 10{sup 6} M{sub Sun} ). We have also identified a population of remote halo GCs. NGC 4449 is consistent with an emerging picture of the ubiquity of stellar halos among dwarf galaxies, and study of its GCs may help distinguish between accretion and in situ scenarios for such halos.

• OSTI ID: 22034708
• Journal Information: Astronomical Journal (New York, N.Y. Online), Journal Name: Astronomical Journal (New York, N.Y. Online) Journal Issue: 2 Vol. 143; ISSN 1538-3881
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ABSORPTION SPECTROSCOPY
ASTRONOMY
ASTROPHYSICS
COLOR
DIAGRAMS
ELEMENT ABUNDANCE
EMISSION SPECTROSCOPY
GALACTIC EVOLUTION
GALAXIES
HYDROGEN
HYDROGEN 1
IRON
MAGNESIUM
PHOTOMETRY
STAR CLUSTERS
TELESCOPES