Evidence of an interacting stellar wind and possible high energy emissionin the open cluster Berkeley 87.

The interaction of the strong (about equal to 5200 km/s) stellar wind from the Wolf-Rayet star ST 3, belonging to the open cluster Berkeley 87, with the cluster stars and molecular clouds appears to produce dissipative shock waves. Optical spectroscopy and imaging of the cluster support this hypothesis. These shocks can give rise to the hard X-ray flux consistent with that detected by Exosat in the cluster-sky area. Shock waves can accelerate the ambient cosmic-ray particles, emitted by the numerous early type stars contained in the cluster, up to highly relativistic energies. This process can possibly explain the observation of high-energy emission of the COS-B source 2 CG 075 + 00 whose error box is centered on Berkeley 87.