NOAO >   Observing Info >   Approved Programs >   2001A-0319

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Proposal Information for 2001A-0319


PI: Stephen Odewahn, Arizona State University, stephen.odewahn@asu.edu
Address: PO 871504, Tempe, AZ 85287-1504, USA

CoI: Rogier Windhorst, Arizona State University
CoI: Margaret Geller, Harvard-Smithsonian, CfA
CoI: Michael Kurtz, Harvard-Smithsonian, CfA

Title: A deep survey of the Coma cluster: Is there a large population of star- forming dwarfs?

Abstract: We request 2 nights with the 8K Mosaic Camera on the KPNO 4-meter to obtain medium-band imaging of a 2.88\sq\deg strip in the Coma cluster. These filters, for the cluster redshift of \z=0.0231, are appropriately tuned to isolate the rest-frame wavelength of key spectral features in star-forming and dwarf spheroidal Coma galaxies. These observations will allow us to \it efficiently isolate thousands of cluster members relative to the background field galaxy population, a job that would be very expensive using spectroscopic followup. Recent ground- and HST-based studies indicate that star-forming dwarf populations may be a fundamental component in clusters. Such a population is believed to produce a steep upturn in some cluster luminosity functions, \it however a lack of deep cluster redshift surveys prevents firm confirmation of this dwarf component. We seek to isolate \it candidate galaxies in Coma which represent the most likely source of the steep faint-end LF reputed to exist by others: star- forming dwarfs with strong emission lines and early-type dwarf spheroidals with 4000\an breaks. There is mounting evidence that such star-bursting components may form structural sub-units in clusters and may be manifestations of the Butcher-Oemler effect seen at high redshift. The large number of high-probability cluster members expected from this medium-band survey will enable us to address these important recent findings concerning cluster populations.


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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