Determination of mass and orbital parameters of a low-mass star HD 213597B

HD 213597 is an eclipsing binary system which was detected by the STEREO spacecraft and was speculated to host a low-mass stellar companion. We used high-resolution spectroscopy with the 10-m Hobby-Eberly Telescope and the 1.2-m telescope in Mount Abu for radial velocity (RV) measurements of this source. We performed aperture photometry for this star on the STEREO archival data and thereby confirm the transit signature. We also did followup ground-based photometry with a 10-inch telescope from Mt Abu. The spectroscopic RV semi-amplitude of the primary (33.39 km s-1) indicates that the secondary is an M dwarf making the system a short period F+Meclipsing binary. These RVs along with the inclination derived from our combined photometric analysis (i = 84. {ring operator} 9), enable us to estimate the mass of the secondary as MB ~ 0.286M ⊙ and radius as RB ~ 0.344 R ⊙ using an estimated mass MA ~ 1.3M ⊙ and radius RB ~ 1.97 R ⊙ of the primary. Our spectral analysis returned the following parameters: Teff = 6625 ± 121 K, [Fe/H]=-0.095 ± 0.08 and log g = 3.72 ± 0.22 for the primary. When log g is constrained to a value of 3.96, we derive T_eff = 6753 ± 52 K and [Fe/H]=-0.025 ± 0.05.