In-depth analysis of the light curve and first orbital period of contact binary GM Dra

Abstract

This study presents the light curve (LC) analysis of the GM Dra eclipsing binary (using data from TESS, SuperWASP, KWS($I_c$), Hipparcos, and ASAS-SN), along with a detailed investigation of its orbital period (OP) for the first time. Photometric data obtained from five different databases were used to simultaneously analyze the system’s LC and radial velocity (RV). The LC modeling results for GM Dra reveal the object stars’ masses and radii as follows: $M_1=0.28\pm 0.01$ M${}_{\odot }$, $M_2=1.34\pm 0.02$ M${}_{\odot }$, $R_1=0.64\pm 0.01$ R${}_{\odot }$, and $R_2=1.27\pm 0.02$ R${}_{\odot }$. A total of 108 eclipse times (ETs) were calculated on the basis of TESS and SuperWASP observations. These ETs are of great significance in determining the OP change. The OP of the GM Dra has been analyzed based on long-term observations, revealing that the OP of GM Dra is decreasing by 0.051 s per year. A sinusoidal variation in the period change was also identified, which may be attributed to the presence of a potential third object or magnetic activity. These findings provide significant insights into the evolutionary status (the positions of the system in the Hertzsprung–Russell (HR) diagram and logM${}_{tot.}$–logJ diagram were discussed) of GM Dra and the dynamics of the binary system.