Journal article
QUIESCENT ISOLATION: THE EXTREMELY EXTENDED H I HALO OF THE OPTICALLY COMPACT DWARF GALAXY ADBS 113845+2008
The Astrophysical journal, Vol.696(2), pp.2104-2114
05/10/2009
DOI: 10.1088/0004-637X/696/2/2104
Abstract
We present new optical imaging and spectroscopy and H I spectral line imaging of the dwarf galaxy ADBS 113845 + 2008 (hereafter ADBS 1138). This metal-poor (Z similar to 30% Z(circle dot)), "post-starburst" system has one of the most compact stellar distributions known in any galaxy to date (B-band exponential scale length = 0.57 kpc). In stark contrast to the compact stellar component, the neutral gas is extremely extended; H I is detected to a radial distance of similar to 25 kpc at the 10(19) cm(-2) level (similar to 44 B-band scale lengths). Comparing to measurements of similar "giant disk" dwarf galaxies in the literature, ADBS 1138 has the largest known H I-to-optical size ratio. The stellar component is located near the center of a broken ring of H I that is similar to 15 kpc in diameter; column densities peak in this structure at the similar to 3.5 x 10(20) cm(-2) level. At the center of this ring, in a region of comparatively low H I column density, we find ongoing star formation traced by Ha emission. We sample the rotation curve to the point of turn over; this constrains the size of the dark matter halo of the galaxy, which outweighs the luminous component (stars + gas) by at least a factor of 15. To explain these enigmatic properties, we examine "inside-out" and "outside-in" evolutionary scenarios. Calculations of star formation energetics indicate that "feedback" from concentrated star formation is not capable of producing the ring structure; we posit that this is a system where the large H I disk is evolving in quiescent isolation. In a global sense, this system is exceedingly inefficient at converting neutral gas into stars.
Details
- Title: Subtitle
- QUIESCENT ISOLATION: THE EXTREMELY EXTENDED H I HALO OF THE OPTICALLY COMPACT DWARF GALAXY ADBS 113845+2008
- Creators
- John M. Cannon - Macalester CollegeJohn J. Salzer - Indiana University BloomingtonJessica L. Rosenberg - George Mason University
- Resource Type
- Journal article
- Publication Details
- The Astrophysical journal, Vol.696(2), pp.2104-2114
- Publisher
- Iop Publishing Ltd
- DOI
- 10.1088/0004-637X/696/2/2104
- ISSN
- 0004-637X
- eISSN
- 1538-4357
- Number of pages
- 11
- Grant note
- Macalester College National Radio Astronomy Observatory National Aeronautics and Space Administration; National Aeronautics & Space Administration (NASA)
- Language
- English
- Date published
- 05/10/2009
- Academic Unit
- Physics and Astronomy
- Record Identifier
- 9984627188202771
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