The Role of Environment in Galaxy Evolution

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Session 87 -- Cluster Evolution
Display presentation, Friday, January 14, 9:30-6:45, Salons I/II Room (Crystal Gateway)

[87.06] The Role of Environment in Galaxy Evolution

P.M. Marcum, J.S.Gallagher (Univ. of WI), P.N. Appleton (Iowa State Univ.)

A fundamental issue in galactic evolution is the relative importance of initial conditions vs environment. To address the role of non-cluster environments, we present near infrared (JHK) data which are the first results of our multi-wavelength study of galaxy groups selected to cover a range in density. The JHK imaging was obtained with the KPNO SQIID detector on the 1.3m telescope as a means of studying the density distributions of stars in galaxies with minimal biases due to the obscuring effects of interstellar dust.

Our sample of groups display a broad range of different environmental conditions: about 1/3 of the groups contain at least one strongly interacting pair, while the remainder of the sample have much lower projected galaxy number densities and consist of more "normal" members. Additionally, the spiral fraction varies significantly among the groups, with a few of the groups consisting almost entirely of either late-type or early-type galaxies. We have searched for correlations between global group parameters (projected galaxy number density, group membership,velocity dispersion) and the presence of strong bars, knots of star formation, and degree of central light concentration among the group members. Surface brightness profiles have been constructed by extracting bright knots, etc. from the smooth underlying luminosity distribution, and are compared for members of different groups having the same Hubble type. Finally, we examine the J-H, H-K colors of the nuclei, disks, and star-forming knots. The results of our near infrared study are discussed in the context of the relationship between galaxy environment and evolutionary histories.

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