The dynamics and structure of the cD galaxy in Abell 2029.

Spectra of the envelope of the cD galaxy in the rich cluster of galaxies Abell 2029 out to over 100 kpc are analyzed by using a Fourier cross-correlation technique. It is found that the measured velocity dispersion apparently increases with radius, implying that the M/L ratio of the envelope is increasing rapidly. All that is presently known about the cluster and the cD galaxy is accounted for by a three-component King (1966) model consisting of a 'normal elliptical' galaxy, a high-M/L cluster-filling and cluster-binding superstructure, and a component of intermediate M/L and velocity dispersion that supplies the light of the 'extended halo'. The high-M/L component is tentatively identified with stripped dark halos of cluster galaxies, and the intermediate-M/L material is attributed to the dynamical friction process that disrupts massive luminous galaxies as they encounter the cD envelope.