Physical Properties of Three Eclipsing Binaries of V Crt, WY Cnc and CG Cyg with Radio Radiation

Abstract

Radio radiation has been detected across the Hertzsprung Russell diagram. We selected three objects with radio radiation (a semi-detached eclipsing binary V Crt, and two detached binaries WY Cnc and CG Cyg) that show magnetic activity. We made new photometric observations using a SARA 60 cm and NAOC 85 cm optical telescopes. Then, we obtained their orbital and starspot parameters by analyzing our light curves and published radial velocities using the updated Wilson-Devinney program. We revised the ephemeris information for V Crt and WY Cnc by analyzing the orbital minimum times. The orbital periods increased by 2.8 (±2.1) ×10−9 d yr−1 for V Crt, which maybe caused by mass transfer. The orbital periods decreased by −8.641 (±0.004) ×10−8 d yr−1 for WY Cnc. Orbital period change for CG Cyg was also found and we used a third-body of M3 of 0.14 M⊙ and a period of approximately 59.20 (0.36) yr to explain that. We also analysed the possible second period oscillation of CG Cyg with a cycle about 18.31 (0.06) yr. The long period changes of WY Cnc and CG Cyg might be caused by magnetic activity or stellar wind, rather than mass transfer.