H II Region Oxygen Abundances in Starbursting Transition Dwarf Galaxies

We present empirical H II region oxygen abundances for a sample of low-luminosity starburst galaxies that are in a short-lived evolutionary state. All five galaxies are characterized by centrally concentrated star formation that is embedded in smooth stellar envelopes resembling dE-like systems. The...

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Bibliographic Details
Published in:The Astrophysical journal 2007-01, Vol.655 (1), p.L29-L32
Main Authors: Dellenbusch, Kate E, Gallagher III, John S, Knezek, Patricia M
Format: Article
Language:English
Subjects:
Astronomy
Earth, ocean, space
Exact sciences and technology
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Summary:We present empirical H II region oxygen abundances for a sample of low-luminosity starburst galaxies that are in a short-lived evolutionary state. All five galaxies are characterized by centrally concentrated star formation that is embedded in smooth stellar envelopes resembling dE-like systems. The galaxies also have small gas contents with typical M super(HI)/L sub(B) 0.1, resulting in gas exhaustion timescales of less than 1 Gyr, even when molecular gas is considered. We find that compared to other morphologically similar systems, the galaxies of this sample have surprisingly high oxygen abundances, with 12 + log (O/H) 6 9.0. We propose that these objects are a subclass of evolved blue compact dwarfs that have exhausted most of their gas supply while retaining their metals. We further propose that we are seeing these objects during a short phase in which they are nearing the end of their starburst activity, and could become early-type dwarfs.
ISSN:1538-4357
0004-637X
1538-4357
DOI:10.1086/511678