The cluster of galaxies Abell 376 . ⋆

We present a dynamical analysis of the galaxy cluster Abell 376 based on a set of 73 velocities, most of them measured at Pic du Midi and Haute-Provence observatories and completed with data from the literature. Data on individual galaxies are presented and the accuracy of the determined velocities is discussed as well as some properties of the cluster. We obtained an improved mean redshift value z = 0.0478 −0.006 and velocity dispersion σ = 852 −76 kms . Our analysis indicates that inside a radius of ∼ 900h 70 kpc (∼ 15 arcmin) the cluster is well relaxed without any remarkable feature and the X-ray emission traces fairly well the galaxy distribution. A possible substructure is seen at 20 arcmin from the centre towards the Southwest direction, but is not confirmed by the velocity field. This SW clump is, however, kinematically bound to the main structure of Abell 376. A dense condensation of galaxies is detected at 46 arcmin (projected distance 2.6 h 70 Mpc) from the centre towards the Northwest and analysis of the apparent luminosity distribution of its galaxies suggests that this clump is part of the large scale structure of Abell 376. X-ray spectroscopic analysis of ASCA data resulted in a temperature kT = 4.3 ± 0.4 keV and metal abundance Z = 0.32 ± 0.08Z⊙. The velocity dispersion corresponding to this temperature using the TX–σ scaling relation is in agreement with the measured galaxies velocities.