Cepheids in Galactic Clusters. I. CF Cass in NGC 7790.

Abstract

Light-curves in three colors have been measured photoelectrically for the classical cepheid CF Cass. This star is very probably a member of the galactic cluster NGC 7790. The double cepheid system CE Cass a and CE Cass b is also probably a cluster member, but no photometric data were obtained for the components A new eclipsing star has been found which may also be a member Both components of the binary are probably Bt V stars with Mv -36 Fragmentary data are given for the star, but no period was found Photometric data for t33 stars in NGC 7790 are given The apparent modulus of the cluster is m-M= 14.35 + 0 15, the reddening is E(B- V) = 0 52 + 004, E(U-B) = 038 + 003 The true modulus is m-M = 12 8 + 0 15 The distance is 3630 + 250 parsecs in the direction 1 = 83?5, b = -0?8 The cepheid CF Cass has a period of 4 87513 days, an amplitude of AV = 0 55 mag, normal mean color indices of (B-V)0 = 072 +004, (U-B)0 = 049 + 003 and mean absolute magnitudes of ME = -2.50+0.15, and Mv = -322 + 0 15