Search for TeV Gamma-Ray Emission from the Young Open Star Clusters Berkeley 87 and IC 1805 with the HEGRA System of Cherenkov Telescopes

Observations of the nearby young open star clusters Berkeley 87 and IC 1805 as well as the COS B source CG135+1 have been carried out in the TeV energy range with the system of Imaging Cherenkov Telescopes of the HEGRA Collaboration. Both clusters contain members with strong stellar winds (up to 5200 km/s for Berkeley 87 and 3800 km/s for IC 1805), favouring shockfront acceleration of cosmic rays. The association of the EGRET source 2EG J2019+3719 with Berkeley 87 and COS B and EGRET sources in the neighbourhood of IC 1805 give a further motivation for VHE observations of these objects and their neighbourhood. No evidence for the emission of TeV gamma rays has been found. The derived upper limits on the integral flux make a significant contribution of young open star clusters to the acceleration of charged Galactic cosmic rays seem unlikely.