Investigating Variable Stars in the Open Cluster NGC 1912 and Its
  Surrounding Field
  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 gamma Doradus stars, one delta
Scuti star, three detached binaries and one contact binaries. 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 gamma Dor stars and two delta Sct stars. The remaining three variable
cluster members, which are all gamma 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.
