AAS 207th Meeting, 8-12 January 2006
Session 188 Galaxy Anatomy: from Bars to Halos
Poster, Thursday, 9:20am-4:00pm, January 11, 2006, Exhibit Hall

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[188.13] High resolution H\,{\sc i} imaging of VIRGOHI 21 - a dark galaxy in the Virgo Cluster

R. F. Minchin (Arecibo Observatory), J. I. Davies, M. J. Disney (Cardiff University), A. R. Marble, C. D. Impey (Steward Observatory), P. J. Boyce, D. A. Garcia, M. Grossi (Cardiff University), C. A. Jordan (Jodrell Bank Observatory), R. H. Lang, S. Roberts (Cardiff University), S. Sabatini (Osservatorio Astronomico di Roma), W. van Driel (Observatoire de Paris)

Dark Matter supposedly dominates the extragalactic Universe, yet no totally dark structure of galactic proportions has ever been convincingly identified. Minchin et al. (2005) suggested that VIRGOHI 21, a 21-cm source found in the Virgo Cluster by Davies et al. (2004), was probably such a dark galaxy because of its broad line-width (~200 km\,s-1) unaccompanied by any visible massive object to account for it. We have now imaged VIRGOHI 21 in the neutral hydrogen line, and indeed we find what appears to be a dark, edge-on, spinning disk with the mass and diameter of a typical spiral galaxy. We also find that there is an indubitable interaction with NGC 4254, a luminous spiral with an odd one-armed morphology but lacking the massive interactor normally linked with such a feature. Published numerical models of NGC 4254 call for a close interaction ~108 years ago with a perturber of ~1011 M\odot. This we take as further, independent evidence for the massive nature of VIRGOHI 21.

The Arecibo Observatory is part of the National Astronomy and Ionosphere Center, which is operated by Cornell University under a cooperative agreement with the National Science Foundation

If you would like more information about this abstract, please follow the link to http://www.naic.edu/~rminchin/virgohi21.html. This link was provided by the author. When you follow it, you will leave the Web site for this meeting; to return, you should use the Back comand on your browser.

The author(s) of this abstract have provided an email address for comments about the abstract: rminchin@naic.edu

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