NOAO >   Observing Info >   Approved Programs >   2008B-0117

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Proposal Information for 2008B-0117


PI: Jayce Dowell, Indiana University, jdowell@astro.indiana.edu
Address: Department of Astronomy, 737 East 3rd Street, Bloomington, IN 47405, USA

CoI: Liese van Zee, Indiana University

Title: Unusually Extended HI Disks and Their Relationship to Damped Ly(alpha) Systems

Abstract: Galaxies with unusually extended HI disks (D_HI/D_B,25 > 5) have been found in both spiral and irregular galaxy types. However, due to a combination of small number statistics and serendipitous discovery, little has been done to establish how these galaxies differ from more normal ones, where the average HI-to-optical diameter ratio is 1.7. In particular, it is not known whether the unusual extent of the gas disk is a result of the formation process or subsequent evolution. In order to better understand the nature and origins of these systems, we are using the ALFALFA survey to create an HI-selected sample of galaxies. Since this sample will contain both galaxies with normal and unusually extended HI disks, it is ideal for quantifying the differences between these two galaxy types and examining the range of impact parameters associated with gas disks. The observations we are proposing for here will be used to determine the star formation properties of a sample of 18 galaxies resolved by the Arecibo beam.


National Optical Astronomy Observatory, 950 North Cherry Avenue, P.O. Box 26732, Tucson, Arizona 85726, Phone: (520) 318-8000, Fax: (520) 318-8360



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