NOAO >   Observing Info >   Approved Programs >   2005A-0392

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Proposal Information for 2005A-0392


PI: John Feldmeier, National Optical Astronomy Observatory, johnf@noao.edu
Address: P.O. Box 26732, Tucson, AZ 85726, USA

CoI: Robin Ciardullo, Penn State University
CoI: George Jacoby, WIYN Observatory
CoI: Pat Durrell, Youngstown State University

Title: Searching for Planetary Nebulae in Ursa Major

Abstract: We propose an [O III] (lambda) 5007 MOSAIC survey for planetary nebulae in the Ursa Major galaxy cluster. These data will be used for two different programs: 1) We will use the [O III] planetary nebula luminosity function to derive the distances to 5 of Ursa Major's spiral galaxies. Despite its importance to the Tully-Fisher distance indicator, there is still no stellar-based distance to the group, and no information on the system's line-of-sight depth. Our observations will produce an independent measure of the intrinsic scatter of the T-F relation, and thereby help constrain models of galaxy formation and evolution.\hfil\linebreak 2) We will use our images of Ursa Major's intracluster space to measure (or place a limit) on the system's intracluster stars. Theory predicts that the amount of intracluster starlight should be a smoothly increasing function of galactic density. However, our previous surveys suggest that the fraction of intracluster stars present drops suddenly (by a factor of ~ 10) as one moves from the richer clusters to the smaller groups. If real, this ``intracluster star cliff'' implies that there is something special about the cluster environment that promotes intracluster star production. Ursa Major lies midway in richness and dwarf galaxy properties between the two cluster regimes studied to date. It is therefore a key environment for constraining the existence and steepness the ``cliff''. This proposal was awarded time last year, but we were clouded out. We are therefore proposing for additional time, and have expanded our focus to include the Tully-Fisher relation for Ursa Major.


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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