Activity of ET Dra—a Star of FK Com Type

Abstract—We present new results of the study of ET Dra—a star of the FK Com type—based on observations carried out at the Zvenigorod Observatory of the Institute of Astronomy of RAS with the help of the FRAM-ORM telescope of the La Palma observatory (Spain) and the broadband optical monitoring system Mini-MegaTORTORA, located on the territory of the SAO RAS. We have studied changes in the shape of the light curve caused by the rotational modulation of a star with spots on its surface and the long-term variability of the star’s brightness. An independent determination of the rotation period of \({{P}_{{{\text{phot}}}}}\) was carried out using all sets of observations available to us. The increase in the brightness of the star near HJD 2459044 during observations with the FRAM-ORM telescope in all three filters was interpreted by us as a stellar flare. Our flare energy estimates are \(2.8 \times {{10}^{{37}}}\), \(1.9 \times {{10}^{{37}}}\), and \(1.5 \times {{10}^{{37}}}\) erg in the \(B\), \(V\), and \(R\) wavelength ranges, respectively. Observations with a duration of more than 2200 days, carried out at the SAO RAS, opened up the possibility of analyzing the long-term brightness variability of ET Dra. Evidence was found for the existence of cycles lasting 580 days and 810 days (1.55 and 2.23 years, respectively).