A Detailed View of the Fundamental Plane of Early-Type Galaxies in Clusters at z~0.2

Abstract

We present a spectroscopic sample of 48 early-type galaxies in the rich cluster Abell 2218 and 50 galaxies in Abell 2390. Since both samples are very similar, we combine them and investigate a total number of 98 early-type galaxies at z~0.2. A subsample of 34 galaxies with HST structural properties is used to construct the Fundamental Plane. Elliptical and S0 galaxies show a zeropoint offset of m_r~0.43 mag with respect to the local Coma FP. Both sub-samples, ellipticals and lenticulars, exhibit a similar, mild evolution and small scatter. The moderate amount of luminosity evolution is consistent with stellar population models of passive evolution, if z_f>=2 is assumed.

3 pages, 2 figures. Uses iaus style. To appear in the proceedings of IAU Colloquium No. 195, "Outskirts of Galaxy Clusters: intense life in the suburbs", ed. A. Diaferio, Torino, Italy, March 12-16, 2004