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Astron. Astrophys. 355, 443-453 (2000)

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Dynamics of the X-ray clusters Abell 222, Abell 223 and Abell 520 *

D. Proust 1, H. Cuevas 2, H.V. Capelato 3, L. Sodré Jr. 2, B. Tomé Lehodey 3, O. Le Fèvre 4 and A. Mazure 4

1 DAEC, CNRS, Observatoire de Paris-Meudon, 92195 Meudon Cedex, France
2 Departamento de Astronomia IAG/USP, Av. Miguel Stefano 4200, 04301-904, São Paulo, Brazil
3 Divisão de Astrofisica INPE/MCT, 12225-010, São José dos Campos, Brazil
4 Laboratoire d'Astronomie Spatiale, Les Trois Lucs, 13012 Marseille, France

Received 10 August 1999 / Accepted 11 January 2000


We present the results of a dynamical analysis of three rich, X-ray luminous galaxy clusters, Abell 222, Abell 223 and Abell 520, that are at intermediate redshifts. Our study is based on radial velocities for 71 cluster members, respectively 30 for A 222, 20 for A 223 and 21 for A 520, measured from spectra obtained at the Canada-France-Hawaii Telescope, the European Southern Observatory, and the Pic du Midi Observatory, and supplemented with radial velocities from the literature. A 222 galaxies have slightly higher velocities than those of A 223, with bi-weighted mean velocity of [FORMULA] for A 222, and of [FORMULA] for A 223. The velocity dispersions of the two clusters are about the same: [FORMULA] and [FORMULA] for A 222 and A 223, respectively. For A 520 we obtain [FORMULA] with [FORMULA]. We also give mass and mass-luminosities ratio estimates for each cluster separately. We argue that these clusters are presently undergoing strong dynamical evolution and that A 222 and A 223 will probably merge in the future. We have applied a Principal Component Analysis to a sample of 51 CFHT spectra to produce a spectral classification for these galaxies. This classification has allowed us to show that the morphological and kinematical segregations were already established in these intermediate redshift clusters.

Key words: galaxies: clusters: general – galaxies: clusters: individual: A 520 – galaxies: clusters: individual: A 222 – galaxies: clusters: individual: A 223 – galaxies: distances and redshifts – cosmology: observations

* based on observations made at ESO-La Silla (Chile), at the Canada France Hawaii Telescope and at the Pic du Midi Observatory (France).

Send offprint requests to: D. Proust

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© European Southern Observatory (ESO) 2000

Online publication: March 9, 2000