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Star formation thresholds in H II galaxies with H I companionsWe present high resolution Very Large Array (VLA) 21 cm line observations of five H II galaxies combined with previous lower resolution data from Taylor et al. (1993) and optical broadband R and H-alpha Charge Coupled Device (CCD) images of the systems. Following Kennicutt (1989) we calculated the threshold H I surface density for star formation for the H II galaxies and compared the location and shape of this predicted threshold density contour with the optical shape of the galaxies. We find generally a good correlation between these two, although a constant density contour of 10(exp 21)/sq cm fits the images of the optical galaxies equally as well. The H I synthesis observations have revealed that the H II galaxies have sharply peaked H I radial profiles, in contrast to the relatively flattened profiles of low surface brightness (LSB) galaxies, suggesting that large central concentrations of gas are a necessary condition for the occurrence of bursts of massive star formation seen in H II galaxies. These observations are consistent with the hypothesis that LSB galaxies represent the quiescent phase of H II galaxies, if a suitable mechanism exists (such as galaxy interactions) to cause H I to concentrate at the center of LSB galaxies prior to the onset of the burst of star formation. However, it is noted that the H II galaxies (and dwarf galaxies in general) span a relatively large range in mass. Since many properties correlate with mass (e.g., gas mass fraction), we point out that great care needs to be taken in choosing the proper comparison samples of LSB and H II galaxies.
Document ID
19950036257
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Taylor, Christopher L.
(Minnesota Univ. Minneapolis, MN, United States)
Brinks, Elias
(National Radio Astronomy Observatory, Socorro, NM United States)
Pogge, Richard W.
(Ohio State Univ. Columbus, OH, United States)
Skillman, Evan D.
(Minnesota Univ. Minneapolis, MN, United States)
Date Acquired
August 16, 2013
Publication Date
March 1, 1994
Publication Information
Publication: Astronomical Journal
Volume: 107
Issue: 3
ISSN: 0004-6256
Subject Category
Astrophysics
Accession Number
95A67856
Funding Number(s)
CONTRACT_GRANT: NSF AST-88-22009
CONTRACT_GRANT: NSF AST-91-12879
CONTRACT_GRANT: NAGW-3189
Distribution Limits
Public
Copyright
Other

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