AAS 201st Meeting, January, 2003
Session 42. Galaxies and Clusters
Poster, Tuesday, January 7, 2003, 9:20am-6:30pm, Exhibit Hall AB

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[42.04] Using Fundamental Plane Distances to Study the Mass of the Abell 2199 and Abell 2197 Cluster Complex

G. A. Wegner (Dartmouth College), J. J. Mohr (University of Illinois)

Relative distances to the galaxy cluster Abell 2199 and two sub-components of the neighboring Abell 2197 cluster, A2197E and A2197W, are derived using the fundamental plane (FP) method from new imaging and spectroscopy obtained using the 2.4 m Hiltner and 3.5 m WIYN telescopes. The new velocity dispersions, \sigma, were combined with the literature data and yield a final sample of 75 early-type galaxies in the clusters. The fundamental planes were fit assuming that the FP parameters are the same, but the clusters are at different distances. For the FP this yields a = 1.25 ± 0.02 and b = 0.34 ±0.01, but the A2197W clump lies 0.05 ±0.01 farther away than A2199 and the smaller A2197E, if separate, is found to be at 0.00 ±0.02. We use the newly measured distances and relative velocities to construct a dynamical model for the complex system. With an estimated virial mass of 1.1 \times 1015 solar masses for the system and an outgoing velocity of about 500 km/s for A2197W relative to A2199, the often used radial infall model cannot provide a bound outgoing orbit for A2197W so a more complicated analysis appears to be required.

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