2019MNRAS.488.4520C

We present observations and analysis of an RS CVn-type double-lined eclipsing binary system, RU Cnc. The system has been observed for over a century. High-quality long-cadence observations, newly obtained from the Kepler K2 C5 and C18 campaigns, and two radial velocity curves were combined and analysed simultaneously, assuming a multispot model. The masses, radii and luminosities of the component stars have been precisely obtained as M_\textrmc = 1.386±0.044 M_☉, M_\textrmh = 1.437 ±0.046 M_☉, R_\textrmh = 2.39±0.07 R_☉, R_\textrmc = 5.02 ±0.08 R_☉, L_\textrmh = 11.4±1.2 L_☉ andL_\textrmc = 12.0 ±1.0 L_☉, with a separation of a = 27.914 ±0.016 R_☉. The distance of the system is determined to be 380±57 pc, which is consistent with the Gaia Data Release 2 result. Long-term detailed period variation analysis of the system indicates a period decrease of 7.9 x 10^–7 d yr^–1. The results suggest that the cooler component is on the red giant branch (RGB) and the hotter component is still on the main sequence.