双星与变星研究组知识库

CU Cancri is an eclipsing binary which is composed of two M-type companions. We detected a large red flare of CU Cnc in the R-band with the 60-cm telescope in Yunnan Astronomical Observatory on October 28, 2009. The amplitude of the flare is about of 0.52 mag and the duration time is about 73 minutes. Another three flares in the same band were detected during 90.8-hours monitoring, which reveal a red flare rate of 0.044 flares per hour. CU Cnc also has other strong chromospheric and coronal emissions. These detections together with the emissions indicate that it has the strongest magnetic activity, and compared with other single red dwarfs of the same mass, CU Cnc is fainter (similar to 1.4 magnitude in V-band). This phenomenon may be plausibly explained by the coverage of the dark spots. That means the coverage of dark spots on red-dwarf eclipsing binaries may be seriously underestimated before.