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Proposal Information for 2006A-0123


PI: John Kormendy, The University of Texas at Austin, kormendy@astro.as.utexas.edu
Address: Department of Astronomy, 1 University Station C1400, Austin, TX 78712-0259, USA

CoI: Mark E. Cornell, The University of Texas at Austin
CoI: David Fisher, The University of Texas at Austin
CoI: Niv Drory, The University of Texas at Austin
CoI: Ralf Bender, Munich Observatory

Title: Structure and Formation of Elliptical Galaxies

Abstract: We propose to use the CTIO 0.9-m to obtain deep surface photometry of all southern elliptical galaxies that have been imaged with HST and that have distances small enough so that core parameters can be derived. The wide-field, single-CCD images from the 0.9-m are the key to good background subtraction and accurate outer profiles. The 0.9-m and HST data will be combined with existing data to derive composite profiles with the highest possible accuracy over the largest possible radius range. The profiles I(r) will be fit with Sersic functions \log I(r) \propto r^1/n. Sersic index n correlates with the dynamical violence of the mergers that form ellipticals. The large dynamic range of our profiles allows us to measure n much more accurately than heretofore possible. Our results will be compared with global and core parameters to determine whether the well-known dichotomy in properties between giant, core ellipticals, and small, coreless ellipticals includes a dichotomy in Sersic n. Previous work based on less accurate n values appeared to show a continuum in values. However, our recent work in Virgo has shown that with accurate Sersic n, the correlations are no longer continuous. The two kinds of ellipticals appear to result from major differences in the dynamical violence of their formation. Our results were derived from the small sample of ~ 30 ellipticals in Virgo and need to be confirmed with a larger sample.


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