AAS 203rd Meeting, January 2004
Session 65 Galaxies
Oral, Tuesday, January 6, 2004, 10:00-11:30am, Regency V

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[65.01] Isolated Elliptical Galaxies

C.E. Aars (Trinity University)

We present the results of a selective search for and the photometric and spectroscopic analysis of nine isolated elliptical galaxies. Selection criteria insure that these objects are separated by at least 2.5 Mpc from any nearest neighbor brighter than MV = -16.5. The extreme isolation of these galaxies makes them ideal laboratories for the study of galaxy evolution, independent of the continual galaxy-galaxy interaction in the clusters within which most ellipticals reside. A comparative density analysis technique was developed to analyze the local environments around the elliptical galaxies with the objective of validating that these objects indeed reside in extremely isolated environments. Verification that these are spheroidal systems is achieved through bulge/disk decomposition using surface photometry, and global colors are compared to expected values. Two-dimensional residual maps produced by model galaxy subtractions are used to search for fine structure in the galaxies. Clues provided by these analyses are used to make preliminary estimates of the past evolutionary history of the galaxies. Stellar population modeling and spectral synthesis techniques are used to determine luminosity-weighted mean ages for the galaxiesí stellar populations and to reveal star forming histories. The highlights of the research are summarized as follows: of the nine candidate galaxies, only six are determined to be true isolated elliptical galaxies. None possess shell structure. Furthermore, the stellar population synthesis performed on the spectra revealed populations younger than 2 Gyr in some of these objects.


The author(s) of this abstract have provided an email address for comments about the abstract: caars@trinity.edu

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Bulletin of the American Astronomical Society, 35#5
© 2003. The American Astronomical Soceity.