Speckle interferometric binary system HD375; Is it a sub-giant binary?

Abstract

Atmospheric modeling is used to build synthetic spectral energy distributions (SEDs) for the individual components of the speckle interferometric binary system HD375. These synthetic SEDs are combined together for the entire system and compared with its observed SED in an iterative procedure to achieve the best fit. Kurucz blanketed models and the measurements of magnitude differences were used to build these SEDs. The input physical parameters for building these best fitted synthetic SEDs represent adequately enough properties of the system. These parameters are: Teffa = 6100 ± 50 K, Teffb = 5940 ± 50 K, log ga = 4.01 ± 0.10, log gb = 3.98 ± 0.10, Ra = 1.93 ± 0.20R⊙, Rb = 1.83 ± 0.20R⊙, Mva = 3·m26 ± 0.40, Mvb = 3·m51 ± 0.50, La = 4.63 ± 0.80 L⊙, and Lb = 3.74 ± 0.70 L⊙, in accordance with the new estimated parallax π = 12.02 ± 0.60 mas. A modified orbit of the system is built and compared with earlier orbits, and the masses of the two components are calculated as Ma = 1.35M⊙ and Mb = 1.25M⊙. Based on the estimated physical and geometrical parameters of the system, which are confirmed by synthetic photometry, we suggest that the two components are evolved subgiant (F8.5 IV and G0 IV) stars with the age of 3.5 Gyr, formed by fragmentation.