Orbital and physical parameters of the close binary system GJ 9830(HIP 116259)

We present the complete set of physical and geometrical parameters of the visual close binary system GJ 9830 for the first time by applying Al-Wardat’s complex method.This method combines magnitude difference from speckle interferometry,synthetic spectral energy distributions of the binary components which are constructed based on grids of Kurucz blanketed models(ATLAS9),and the orbital solution using Tokovinin’s dynamical method to estimate the parameters of individual components.The analysis of the system by employing synthetic photometry resulted in the following set of parameters:Teff= 6220 ± 100 K,log g = 4.30 ± 0.12,R = 1.10 ± 0.08 R⊙for the primary component and Teff= 4870 ± 100 K,log g = 4.60 ± 0.11,R = 0.709 ± 0.07 R⊙for the secondary component.The recently published dynamical parallax from the Gaia space mission was used to calculate the total mass of the binary system as 1.75 ± 0.06 M⊙,which coincides with those estimated using Al-Wardat’s method as MA= 1.18 ± 0.10 M⊙,MB= 0.75 ± 0.08 M⊙.The analysis of the system reveals that both components are characteristic of main sequence stars and have an age of around 1.4 ± 0.50 Gyr.The evolutionary tracks and isochrones of the system’s components are discussed,and the fragmentation process is suggested as the most likely process for the formation of the system.

PS Vir:a short-period solar-like contact binary

We present multi-color photometric observations and a one-dimensional spectrum, acquired from March 2016 to May 2017, for the short-period eclipsing binary PS Vir, by using the 2.16-m, 85-cm and 60-cm telescopes at Xinglong station, which is administered by National Astronomical Observatories, Chinese Academy of Sciences. The spectral type was determined as G2V from the one-dimensional spectrum. The photometric solution was reduced from BVRc light curves. The results imply that PS Vir is a W-subtype contact binary with a mass ratio of q - 0.305（zk0.008） and a fill-out factor of f = 14.4（＋1.8）%. The orbital period may be undergoing a cyclic oscillation with an ampli-tude of A = 0.0027（~0.0001）d and a modulated period of 11.7（4-0.2） yr, which may result from the light-time effect due to a third body. The lower limit on mass for the assumed component is 0.12 Me. Moreover, the more massive component of PS Vir may be a bit more evolved star as determined from the mass-luminosity diagram.

IU Cancri:a solar-type contact binary with mass transfer

We present new CCD photometry of the solar-type contact binary IU Cnc, which was observed from November 2017 to March 2018 with three small telescopes in China. BV light curves imply that IU Cnc is a W-type contact binary with total eclipses. The photometric solution indicates that the mass ratio and fill-out factor are q = 4.104 ± 0.004 and f = 30.2%± 0.3%, respectively. From all available light minimum times, the orbital period may increase at a rate of dP/dt =+6.93(4)× 10^-7 d yr^-1, which may result from mass transfer from the secondary component to the primary one. With mass transferring,IU Cnc may evolve from a contact configuration into a semi-detached configuration.