Periodic Variables in the Open Cluster NGC 2301

TL;DR

This study identified 138 periodic variables in the open cluster NGC 2301, analyzed their period-color relationship, and estimated the cluster's age, providing insights into stellar rotation and activity.

Contribution

It is the first comprehensive analysis of periodic variables in NGC 2301, including a test of the Barnes (2003) period-color interpretation and an age estimate.

Findings

138 periodic variables discovered, including 5 eclipsing binaries.

Cluster age estimated at 210±25 Myr, consistent with previous studies.

No clear I and C sequences observed in the period-color plane, likely due to field star contamination.

Abstract

We present the results of a search for periodic variables within 4078 time-series light curves and an analysis of the period-color plane for stars in the field of the open cluster NGC2301. One hundred thirty-eight periodic variables were discovered, of which five are eclipsing binary candidates with unequal minima. The remaining 133 periodic variables appear to consist mainly of late-type stars whose variation is due to rotation modulated by star spot activity. The determined periods range from less than a day to over 14 days and have nearly unreddened B-R colors in the range of 0.8 to 2.8. The Barnes (2003) interpretation of the period-color plane of late type stars is tested with our data. Our data did not show distinct I and C sequences, likely due to nonmember field stars contaminating in the background, as we estimate the total contamination to be 43%. Using different assumptions, the gyrochronological age of the cluster is calculated to be 210+/-25 Myr, which falls in the range of age values (164-250 Myr) determined by previous studies. Finally, we present evidence which nullifies the earlier suggestion that two of the variable stars in NGC2301 might be white dwarfs.