view Abstract Citations (33) References (26) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Bound Populations around cD Galaxies Bothun, Gregory D. ; Schombert, James M. Abstract Velocity measurements of a complete sample of galaxies within a projected separation of 200 kpc and L > 0.5 L_*_ are presented for the cD clusters A2271, A2589, and A2634. For A2271 and A2634, the distribution of velocities are consistent with Gaussian distributions with dispersions of 460 and 842 km s^-1^, respectively. In contrast, A2589 contains a conspicuous excess of low-velocity galaxies (|{DELTA}v| < 200 km s^-1^) in the cluster core. We present evidence that this low-velocity component represents a bound population of satellite galaxies to the central cD galaxy. For this bound population, the dynamical friction time scale is significantly less than the Hubble time and therefore these galaxies should eventually merge with the cD. However, our remaining two clusters do not exhibit such dramatic evidence for a bound population, and the data of Tonry also indicate that mostly high-velocity companions are found in the vicinity of brightest cluster members. In addition, a recent velocity study around the cD galaxy in A2029 by Bower, Ellis, and Efstathiou has failed to discover a low-velocity component. Thus, if cD galaxies are the result of mergers, this dynamical evolution occurred early in the lifetime of rich clusters. In this context, A2589 is postulated to be unique since the merger process is still continuing. Moreover, a comparison between the observed tidal radii of the companions in A2589 with the dynamical friction time scale demands that the orbits be highly noncircular, else this population would have long since been destroyed. Publication: The Astrophysical Journal Pub Date: December 1988 DOI: 10.1086/166953 Bibcode: 1988ApJ...335..617B Keywords: Galactic Clusters; Galactic Evolution; Galactic Nuclei; Red Shift; Velocity Distribution; Hubble Constant; Normal Density Functions; Stellar Evolution; Astrophysics; GALAXIES: CLUSTERING; GALAXIES: REDSHIFTS full text sources ADS | data products SIMBAD (43) NED (43)