Studies of Yellow Semiregular(SRd) Variables

We have used the Hipparcos database of epoch photometry to study the variability of several yellow semiregular(SRd) variables. For some of the stars (V847 Cas, RW Cep, BM Sco, CE Vir), the results were inconclusive. For SX Lac and TY Vir, the periods found were consistent with the General Catalogue of Variable Stars (190 and 50 days respectively). For UU Her, the known periods of about 45 and 72 days were recovered. For WY And, RU Cep, and SX Her, reliable periods were found; we used archival data to construct (O-C) diagrams to study both the random and systematic period changes in these three stars.