Variable stars in the open cluster Mel 71

The UBVI and time-series CCD photometric observations of the intermediate-a ge open cluster Mel 71 were carried out to search for variable stars and ob tain their physical parameters. By fitting the ZAMS to the observed color-c olor and color-magnitude diagrams, we estimated a reddening value of the cl uster E(B-V) = 0.20 +/- 0.05 and a distance modulus (V-M-V)(o) = 11.6 +/- 0 .2. We also found its age of about log t = 9.0 from an isochrone fitting me thod for Z = 0.008. Using the observed time-series data, we carefully examined light variations of 358 stars, fainter than 13.(m)0. Four 6 Set stars and one eclipsing bin ary were discovered. They are located in the 6 Set instability strip of the color-magnitude diagram. Incidence of variability within the instability s trip is about 7%. Newly found delta Set 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.