TX Cnc AS A MEMBER OF THE PRAESEPE OPEN CLUSTER

We present B-, V-, and I-band CCD photometry of the W UMa-type binary system TX Cnc, which is a member star of the Praesepe open cluster. Based on the observations, new ephemeris and a revised photometric solution of the binary system were derived. Combined with the results of the radial velocity solution contributed by Pribulla et al., the absolute parameters of the system were determined. The mass, radius, and luminosity of the primary component are derived to be 1.35 ± 0.02 M sun, 1.27 ± 0.04 R sun, and 2.13 ± 0.11 L sun. Those for the secondary star are computed as 0.61 ± 0.01 M sun, 0.89 ± 0.03 R sun, and 1.26 ± 0.07 L sun, respectively. Based on these results, a distance modulus of (m - M) V = 6.34 ± 0.05 is determined for the star. It confirms the membership of TX Cnc to the Praesepe open cluster. The evolutionary status and the physical nature of the binary system are discussed compared with the theoretical model.