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Probing Globular Cluster Formation in Low Metallicity Dwarf Galaxies

Published online by Cambridge University Press:  01 June 2008

Kelsey E. Johnson ,
Leslie K. Hunt  and
Amy E. Reines
Kelsey E. Johnson
Affiliation:
Astronomy Department, University of Virginia, P.O. Box 400325, Charlottesville, VA, 22904, USA email: [email protected] The National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903, USA
Leslie K. Hunt
Affiliation:
INAF-Istituto di Radioastronomia-Sez. Firenze, L.go, Fermi 5, I-50125 Firenze, Italy
Amy E. Reines
Affiliation:
Astronomy Department, University of Virginia, P.O. Box 400325, Charlottesville, VA, 22904, USA email: [email protected]
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Abstract

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The ubiquitous presence of globular clusters around massive galaxies today suggests that these extreme star clusters must have been formed prolifically in the earlier universe in low-metallicity galaxies. Numerous adolescent and massive star clusters are already known to be present in a variety of galaxies in the local universe; however most of these systems have metallicities of 12 + log(O/H) > 8, and are thus not representative of the galaxies in which today's ancient globular clusters were formed. In order to better understand the formation and evolution of these massive clusters in environments with few heavy elements, we have targeted several low-metallicity dwarf galaxies with radio observations, searching for newly-formed massive star clusters still embedded in their birth material. The galaxies in this initial study are HS 0822+3542, UGC 4483, Pox 186, and SBS 0335-052, all of which have metallicities of 12 + log(O/H) < 7.75. While no thermal radio sources, indicative of natal massive star clusters, are found in three of the four galaxies, SBS 0335-052 hosts two such objects, which are incredibly luminous. The radio spectral energy distributions of these intense star-forming regions in SBS 0335-052 suggest the presence of ~12,000 equivalent O-type stars, and the implied star formation rate is nearing the maximum starburst intensity limit.

Keywords

galaxies: star clustersgalaxies: starburstHII regionsstars: formation
Type
Contributed Papers
Information
Proceedings of the International Astronomical Union , Volume 4 , Issue S255: Low-Metallicity Star Formation: From the First Stars to Dwarf Galaxies , June 2008 , pp. 366 - 369
Copyright
Copyright © International Astronomical Union 2008

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