AGES AND MASSES OF DELTA-SCUTI STARS IN THE PRAESEPE CLUSTER

Physical parameters and radial pulsation modes are determined for three Delta Scuti stars in the Praesepe cluster: HD 73345, HD 73712, and HD 73746. Their ages t and evolutionary masses M(e) are interpolated in the track systems of Iben (1967) and Paczynski (1970). By combining these age estimates with our previous results for nine other Delta Scuti-stars in the Praesepe cluster (Tsvetkov, 1989), the following weighted mean age estimates of this cluster are obtained: (14.2 +/- 1.3) x 10(8) yr (Iben) and (5.4 +/- 0.4) x 10(8) yr (Paczynski). Age and evolutionary mass estimates of the twelve cluster variables are also obtained in the modem track system of Maeder and Meynet (1988), in which the weighted mean cluster age is (15.3 +/- 1.0) x 10(8) yr. Pulsation masses M(Q) calculated from the fitting formulae of Faulkner (1977) and Fitch (1981) as well as masses M(q) = gR2/G were evaluated for the twelve cluster variables by Tsvetkov (1990) or in the present paper. In most cases there is a satisfactory agreement between our estimates of masses M(e), M(g), and M(Q). Due to a large disagreement between the long period and low luminosity of the star HD 73746, its radial pulsation mode and pulsation mass M(Q) cannot be evaluated.