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C.E. Aars, P.M. Marcum (Texas Christian University), M.N. Fanelli (University of North Texas)
Because most galaxies tend to exist in associations that range in density from loose groups to rich clusters, mergers and interactions play dominant roles in the evolution of a typical galaxy. Thus, elliptical galaxies isolated from their nearest neighbors by great distances (more than 2.5 Mpc) preclude ongoing interaction. This gives them a unique evolutionary history, allows for evaluation of the overall importance of interaction and merger in elliptical galaxy formation and evolution, and provides a basis for the determination of the time scales involved in the appearance and disappearance of the signatures of galaxy merger. In addition, the combination of their morphology and isolation provides a rare opportunity to study some of the oldest stellar systems known in the universe. Projection effects make verifying the isolation of an elliptical galaxy extremely difficult. The relative dimness and, in some cases, sheer quantity of objects angularly close to a candidate isolated elliptical makes obtaining redshifts without the use of a multi-fiber spectrometer impractical or impossible. Thus, a method of identifying objects as galaxies near a candidate isolated elliptical, and determining if they are physical neighbors or the result of projection effects, without the use of redshift data, is presented, applied to a subset of elliptical galaxies in the Karachenseva (SaSAO 1973) catalog.
The author(s) of this abstract have provided an email address for comments about the abstract: ceaars@delta.is.tcu.edu