Distribution of Cool Starspots on the Surface of the Red Dwarf V647 Her

Abstract

Abstract An analysis of photometric observations of the star V647 Her (M3.5V) obtained at the 1.25-m telescope of the Crimean Astrophysical Observatory in 2022 is presented. The presence of a low-amplitude variability in brightness of the star with a period of 20.69 d, found from observations in 2019 was confirmed. It is shown that as the brightness decreases, the star becomes redder. The observed kind of photometric variability is due to the presence of cool spots on the surface of the star and rotational modulation of brightness with a full amplitude of no more than 0$$^{{\text{m}}}_{.}$$05. We perform a comparison of the photometric results obtained in 2019, 2022, and 2004. The locations of starspots at different epochs were determined from the analysis of phase curves. The distribution of starspots has been maintained for 40–100 days. Starspot parameters were estimated in the framework of the zonal model. The temperature of starspots is 2700–2800 K. The area they occupied in 2004 is 15% of the total surface area of the star. According to the 2019 and 2022 data, it increases up to 30%. The seasonal redistribution of starspots leads to the difference between the spottedness of hemispheres, which is less than 2%.