Journal Article

Optical flares and flaring oscillations on the M-type eclipsing binary CU Cancri

S.-B. Qian, J. Zhang, L.-Y. Zhu, L. Liu, W.-P. Liao, E.-G. Zhao, J.-J. He, L.-J. Li, K. Li and Z.-B. Dai

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 423, issue 4, pages 3646-3651
Published in print July 2012 | ISSN: 0035-8711
Published online July 2012 | e-ISSN: 1365-2966 | DOI:
Optical flares and flaring oscillations on the M-type eclipsing binary CU Cancri

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In this paper, we report on the discovery of an optical flare observed in the R band from the red-dwarf eclipsing binary CU Cancri, whose component stars are at the upper boundary of full convection (M1= 0.43 M and M2= 0.4 M, where M is the solar mass). The amplitude of the flare is the largest among those detected in the R band (∼0.52 mag) and the duration time is about 73 min. Like flares observed on the Sun, quasi-periodic oscillations were seen during and after the flare. Three more R-band flares were found by follow-up monitoring. In total, this binary was monitored photometrically by using an R filter for 79.9 h, which has revealed an R-band flare rate of about 0.05 flares per hour. Together with other strong chromospheric and coronal activities (i.e. very strong Hα and Hβ emission features and an extreme ultraviolet and X-ray source), these detections indicate that it has very strong magnetic activity. Therefore, the apparent faintness (∼1.4 mag in the V band) of CU Cnc, compared with other single red dwarfs of the same mass, can be plausibly explained by the high coverage of dark spots.

Keywords: stars: activity; binaries: close; binaries: eclipsing; stars: flare; stars: individual: CU Cancri; stars: late-type

Journal Article.  3744 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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