Rotational modulation and flares on RS CVn and BY Dra stars. XX. Photometry and spectroscopy of CC Eri in late 1989

Abstract

The active flaring binary CC Eri was studied via multi-wavelength observations involving multi-based photometry and ground- and space-based spectroscopy. Combining early spectroscopic data with the present implies an orbital period of P=1.5615 days. Furthermore, the spectroscopic data suggests spectral types of K7 and M3 for the system. The optical photometry indicated a small spot coverage in late 1989, consistent with data taken a year later which showed CC Eri entering its brightest-to-date phase. Two flares were detected in the ultraviolet spectral data. These flares radiated 2.7 10³¹ erg and 1.6 10³¹ erg in the C Iv line alone, each with a total estimated radiative energy budget of ~ 10³⁶ erg. For the higher-temperature lines, such as C Iv, there was no systematic variability with phase. The lower-temperature lines show a slight indication of rotational modulation. However, there is a much larger scatter in the individual measurements of the Mg Ii and C Iv fluxes than would be expected from measurement errors alone, consistent with an atmosphere showing continual small-scale activity.