Vol 21, No 3

Investigating variable stars in the open cluster NGC 1912 and its surrounding field

Chun-Yan Li, Ali Esamdin, Yu Zhang, Fang-Fang Song, Xiang-Yun Zeng, Li Chen, Hu-Biao Niu, Jian-Ying Bai, Jun-Hui Liu


Abstract In this work, we studied the variable stars in the open cluster NGC 1912 based on the photometric observations and Gaia DR2 data. More than 3600 CCD frames in B, V, R filters were reduced, and we obtained the light curves that span about 63 hours. By analyzing these light curves, we detected 24 variable stars, including 16 periodic variable stars, seven eclipsing binaries and one star whose type is unclear. Among these 24 variable stars, 11 are newly discovered, which are classified as six γ Doradus stars, one δ Scuti star, three detached binaries and one contact binary. We also confirmed 13 previously known variable stars. Based on cluster members identified by Cantat-Gaudin et al. (2018), we inferred cluster memberships for these detected variable stars. Using Gaia DR2 data, we plotted a new color-magnitude diagram for NGC 1912, and showed the nature of variable cluster members in kinematical properties and heliocentric distance. Among the 24 variable stars, seven variables are probable cluster members, which show homogeneity in kinematic characters and space position with the established cluster members. Four of the seven variable cluster members are the previously discovered stars, consisting of two γ Dor stars and two δ Sct stars. The remaining three variable cluster members, which are all γ Dor stars, are firstly detected in this work. The main physical parameters of these variable cluster members estimated from the color-magnitude diagram are log(age/yr) = 8.75, [Fe/H] = −0.1, m − M = 10.03 mag, and E(B − V ) = 0.307.


Keywords open clusters and associations: NGC 1912 — techniques: photometric — stars: variables: general

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