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Variable stars in the open cluster Mel 71
B.-G. Park and
Received 4 March 1999 / Accepted 22 June 1999
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-MV) = 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 . Four Sct stars and one eclipsing binary were discovered. They are located in the Sct instability strip of the color-magnitude diagram. Incidence of variability within the instability strip is about 7%. Newly found Sct stars show complex light variations, implying that they have multiple pulsation frequencies. The period of the binary star is estimated to be about .
Key words: Galaxy: open clusters and associations: individual: Mel 71 stars: variables: ffi Sct stars: binaries: eclipsing
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Online publication: August 13, 199