A search for variable stars in the open clusters NGC7209, NGC1582 and Dolidze 18

CCD time-series photometric observations are presented for the stars in the fields of the open clusters NGC7209, NGC1582 and Dolidze 18 in Johnson V, together with some photometric observations in R, and B. The results reveal 14 variable stars in the three clusters in total, among which 13 are newly-discovered variables. With color–magnitude diagrams and color–color diagram, memberships of the variable stars are estimated. With the derived light curves, scales of time and amplitude of variability of these variable stars are obtained. Together with the spectral types due to the estimation of color temperatures, possible types of the variable stars are preliminarily discussed.

► We present CCD time-series observations in Johnson V and R (some also in B) in the fields of three open clusters. ► We found altogether 14 variables in three open clusters, 13 of them are newly discovered variable stars. ► We obtained color–magnitudes diagrams for NGC7209 and NGC1582 and Dolidze 18, color–color diagram for Dolidze 18. ► We estimate several properties for the variable stars.