Investigating stellar variability in the open cluster region NGC 381

TL;DR

This study analyzes variable stars in NGC 381, identifying different types including eclipsing binaries, pulsating stars, and rotational variables, and estimates their physical parameters using photometric data and modeling software.

Contribution

It provides a detailed classification and physical parameter estimation of variable stars in NGC 381, including the first identification of several types within this cluster.

Findings

Identified 57 variable stars, including 5 cluster members.

Estimated ages of EW binaries are > 0.6 Gyr, consistent with formation constraints.

Determined pulsation modes and physical parameters for select variables.

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 out of which five 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 out of which 2 are Algol type (EA) while 8 are W UMa type (EW) binaries. 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 estimation of the physical parameters of the three EW type binaries is done using PHOEBE model-fitting software. The pulsating variable stars include one each from {\delta} Scuti and {\gamma} Dor variability class. We determined the pulsation modes of pulsating variables with the help of the FAMIAS package. We obtained 15 rotational variables stars comprising four dwarf stars identified on the basis log(g) versus log(Tef f ) diagram. These dwarf stars are found to have generally larger periods than the remaining rotational variables.