Investigating Stellar Variability in the Open Cluster Region NGC 381

Abstract

We study variable stars in the field of the open cluster NGC 381 using photometric data observed over 27 nights and identify a total of 57 variable stars, six of which are member stars. The variable stars are classified based on their periods, amplitudes, light-curve shapes, and locations in the H-R diagram. We found a rich variety of variable stars in the cluster. We identified a total of 10 eclipsing binaries, of which two are of Algol type while eight are of W UMa type (EW). The estimated ages of these EW binaries are greater than 0.6 Gyr, which is in agreement with the formation time constraint of 0.6 Gyr on short-period eclipsing binaries. The physical parameters of the two EW-type binaries are estimated using PHOEBE model-fitting software. The pulsating variable stars include one each from the δ Scuti and γ Dor variability classes. We determined the pulsation modes of pulsating variables with the help of the FAMIAS package. We obtained 15 rotational variable stars comprising four dwarf stars identified on the basis of their log(g) versus log(Teff) diagram. These dwarf stars are found to have generally longer periods than the remaining rotational variables.