The Carina Project. VI. The helium burning variable stars
We present new optical (BVI) time-series data for the evolved variable stars in the Carina dwarf spheroidal galaxy. The quality of the data and the observing strategy allowed us to identify 14 new variable stars. Eight out of the 14 are RR Lyrae (RRL) stars, four are Anomalous Cepheids (ACs) and two are geometrical variables. Comparison of the period distribution for the entire sample of RRLs with similar distributions in nearby dSphs and in the Large Magellanic Cloud indicates that the old stellar populations in these systems share similar properties. This finding is also supported by the RRL distribution in the Bailey diagram. On the other hand, the period distribution and the Bailey diagram of ACs display significant differences among the above stellar systems. This evidence suggests that the properties of intermediate-age stellar populations might be affected both by environmental effects and structural parameters.
Authors: G. Coppola, P.B. Stetson, M. Marconi, G. Bono, V. Ripepi, M. Fabrizio, M. Dall'Ora, I. Musella, R. Buonanno, I. Ferraro, G. Fiorentino, G. Iannicola, M. Monelli, M. Nonino, I. Pulone, F. Thévenin, A.R. Walker