Photometric observations of NGC 281: Detection of 228 variable stars

TL;DR

This study used time series photometry to identify and classify 228 variable stars in the young open cluster NGC 281, including main-sequence and pre-main-sequence types, and distinguished cluster members from field stars.

Contribution

It is the first comprehensive identification and classification of variable stars in NGC 281, including new potential variable types and detailed membership analysis.

Findings

81 variables are cluster members, with 30 main-sequence and 51 pre-main-sequence.

Main-sequence variables include $eta$ Cep, $ ext{delta}$ Scuti, and slowly pulsating B stars.

Field variables likely include RR Lyrae, $ ext{delta}$ Scuti, and binary stars.

Abstract

We identify 228 periodic variables in the region of young open cluster NGC 281 using time series photometry carried out from 1 m class ARIES telescopes, Nainital. The cluster membership of these identified variables is determined on the basis colour-magnitude, two colour diagrams and kinematic data. Eighty one variable stars are found to be members of the cluster NGC 281. Of 81 variables, 30 and 51 are probable main-sequence and pre-main-sequence members, respectively. Present study classifies main-sequence variable stars into different variability types according to their periods of variability, shape of light curves and location in the Hertzsprung-Russell diagram. These identified main-sequence variables could be $\beta$ Cep, $\delta$ Scuti, slowly pulsating B type and new class variables. Among 51 pre-main-sequence variables, majority of them are weak line T Tauri stars. The remaining 147 variables could belong to the field population. The variability characteristics of the field population indicate that these variables could be RR Lyrae, $\delta$ Scuti and binaries type variables.