Photometric and Spectroscopic Studies of the Long-Period Low-Mass-Ratio Deep-Contact Binary KN Per

• Published in: Publications of the Astronomical Society of the Pacific 2022-11, Vol.134 (1041), p.114202
• Main Authors: Gao, Xin-Yi, Li, Kai, Cai, Ya-Wen, Guo, Ya-Ni, Gao, Xing, Wang, Xi, Yin, Shi-Peng, Liu, Fei, Sun, Guo-You
• Format: Article
• Language: English
• Subjects: Binary stars; Chromospheric activity; Contact binary stars; Eclipsing binary stars; Emission lines; Magnetic stars; Mass transfer; Observatories
• ISSN: 0004-6280; 1538-3873
• DOI: 10.1088/1538-3873/ac99fd

Photometric analysis and spectroscopic study of the long-period low-mass-ratio deep-contact binary KN Per were performed. The light curves of the BV ( RI ) c band were from the Ningbo Bureau of Education and Xinjiang Observatory Telescope at the Xingming Observatory. Through the analysis of the Wilson–Devinney program, KN Per was found as an A-type low-mass-ratio deep-contact binary ( q = 0.236; f = 53.4%). A cool spot applied on the primary component was introduced to explain the unequal maxima of the light curve. Based on the O − C analysis, we found that the rate of the increasing orbital period is P ̇ = 5.12 ± (0.30) × 10 −7 day yr −1 , meaning the mass transfer from the secondary component to the primary one. By analyzing the spectroscopic data, we detected chromospheric activity emission line indicators, which correspond to the light-curve analysis. Seventy-one long-period ( P > 0.5 day) contact binaries, including our target, were collected. The evolutionary states of all collected stars were investigated by the illustrations of mass–radius, mass–luminosity, and log M T –log J o . The relations of some physical parameters were also determined. With the instability parameters of KN Per, we determined that it is a stable contact binary system at present.