A search for evolutionary changes in the periods of Cepheids using archival data from the Harvard observatory plate collection I: VY, WZ and GH Carinae

Abstract

2052 magnitude estimates for the Cepheids VY Car, WZ Car and GH Car were made using plates from the Harvard College Observatory photographic plate collection. The data complemented 2398 photoelectric measurements in the B and V filters of the Johnson system, essentially extending the time baselines of O‒C data for the stars, which now span more than one century. Evolutionary changes in pulsation period were established for WZ Car and GH Car and were improved for VY Car.