NOAO >   Observing Info >   Approved Programs >   2003A-0426

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Proposal Information for 2003A-0426


PI: Sheila Kannappan, The University of Texas at Austin, sheila@astro.as.utexas.edu
Address: McDonald Observatory, 1 University Station C1402, Austin, TX 78712-0259, USA

CoI: Chris Impey, University of Arizona

Title: Faint Companions and LSB Extensions of S0 Galaxies: Clues to HSB Disk Formation

Abstract: We propose to use the 4-meter telescope at KPNO to complete our deep ((mu)_\rm V=27) MOSAIC imaging survey of 25 S0 galaxies to study their extended disk structures and environments. As a heterogeneous population shaped to varying degrees by galaxy encounters, cluster influences, and secular evolution, S0's are ideal for studying the interplay of internally and externally driven processes in HSB disk formation. Our sample is broadly representative of this population over a wide range of luminosities and environments. Comparably sensitive data have not been available for such a sample: the proposed data will allow us to detect companions as faint as Local Group dwarf spheroidals as well as extended LSB structures as faint as the disk of Malin 1. With extensive supporting data from previous surveys, the final data set will allow us to correlate disk properties (e.g., scale lengths or heights for the main disk and any LSB extensions, truncation radii, v/\sigma ratios, and star formation rates) against indicators of different disk formation mechanisms (e.g., companion distances and sizes, global environmental densities, and disk gas metallicities), to evaluate the respective roles of secular and externally driven evolution in S0 disk formation. We have been allocated 2 nights with MOSAIC in 2002B to image the 10 galaxies in our sample that are observable in the fall. Here we request 3 spring nights for the remaining 15 galaxies, which are essential to a final sample that permits separation of the effects of luminosity and local and global environment.


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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