Multiwavelength Campaign Observations of a Young Solar-type Star, EK Draconis. III. Comparison between Starspot Mapping, Zeeman Doppler Imaging, and Multiwavelength Variability
Journal Article
Overview
abstract
Abstract; ; Recent simultaneous multiwavelength observations of a nearby young solar-type star EK Draconis (EK Dra) in the optical, H; α; spectrum, and X-ray, have provided evidence for stellar prominence eruptions associated with superflares. The large prominence eruption is suggested to have been caused by a large mid-latitude spot on the polarity inversion lines near the stellar limb from concurrent Zeeman Doppler imaging (ZDI) and optical photometry from TESS. In this study, we perform starspot mapping of EK Dra using TESS data to investigate the relation between starspots and magnetic fields from the photometry and ZDI. We also explore the multiwavelength rotational variability ascribed to starspots and active regions in TESS, B-band, H; α; , and X-ray light curves. As a result, we find that (i) spot locations deduced from the TESS light curve are mostly consistent with the intensity map from the ZDI except for a polar spot, and (ii) the H; α; light curve exhibits clear periodicity with respect to the TESS light curve because the H; α; line is radiated around spots in the chromosphere. The X-ray light curve does not show such an association, probably because of multiple spots at a high activity level and the extended spatial structure of coronal active regions. The results provide clues to explore their association with stellar flares at different heights of active regions in chromospheric and coronal lines. Our study also enables us to quantify the stellar X-ray and ultraviolet radiation from the magnetic fields of active stars toward understanding the atmospheric evolution of exoplanets.;
