KIC 6362386: An Eclipsing Binary with γ Doradus–type Pulsations and Starspots

Abstract

KIC 6362386 is an eclipsing binary system that exhibits both γ Doradus ( γ Dor)–type pulsations and starspots. In this study, we investigated this binary system using the Kepler photometry and the spectroscopic data from the Large Sky Area Multi-Object Fiber Spectroscopic Telescope. After employing the PHOEBE program for light-curve and radial-velocity-curve synthesis, analyses reveal that the binary is a circle ( e ∼ 0.0006), has a small mass ratio ( q ∼ 0.311), and is a detached system consisting of an F-type primary star and an M-type secondary star with masses and radii of M _1 = 1.43 ± 0.13 M _⊙ , R _1 = 1.68 ± 0.08 R _⊙ and M _2 = 0.44 ± 0.18 M _⊙ , R _2 = 0.46 ± 0.06 R _⊙ , respectively. Utilizing the Padova isochrone, we estimate the age of the binary system to be ${1.58}_{-0.13}^{+0.15}$ Gyr. By analyzing the out-of-eclipse residuals, we identify variations in the residuals attributed to both starspots and stellar pulsations. The autocorrelation function analysis indicates the decay time of starspots is approximately 37 days with the rotation period aligning with the orbital period. Considering the masses, radii, and positions of the two components on the Hertzsprung–Russell diagram, we deduce that the γ Dor–type g-mode pulsations came from the primary star where the main frequency is 0.1642c/d. Consequently, KIC 6362386 becomes a valuable target for the investigation of γ Dor–type pulsations and asteroseismology in a binary system.

Keywords

• Starspots
• Stellar physics
• Gamma Doradus variable stars
• Pulsating variable stars
• Binary stars