Variable stars in the open cluster Mel 71

The UBVI and time-series CCD photometric observations of the intermediate-age open cluster Mel 71 were carried out to search for variable stars and obtain their physical parameters. By fitting the ZAMS to the observed color-color and color-magnitude diagrams, we estimated a reddening value of the cluster E(B−V) = 0.20 ± 0.05 and a distance modulus (V−M V) • = 11.6 ± 0.2. We also found its age of about log t = 9.0 from an isochrone fitting method for Z = 0.008. Using the observed time-series data, we carefully examined light variations of 358 stars, fainter than 13. m 0. Four δ Sct stars and one eclipsing binary were discovered. They are located in the δ Sct instability strip of the color-magnitude diagram. Incidence of variability within the instability strip is about 7%. Newly found δ Sct stars show complex light variations, implying that they have multiple pulsation frequencies. The period of the binary star is estimated to be about 0. d 678.