Surface activity of rapidly rotating stars from simultaneous X-ray and UV observations with AstroSat

Abstract: Our study focuses on analysing the coronal, transition and chromospheric activity of four rapidly rotating stars located within 50 pc in the solar neighbourhood. We have used the multi-wavelength capabilities of AstroSat, to investigate the outer atmospheres of AB Dor, BO Mic, DG CVn and GJ 3331. These stars, classified as M and K type active stars, are known for their short rotation periods, leading to increased surface magnetic activity. Our soft X-ray observations provide the coronal properties such as emission measures, temperatures and elemental coronal abundances. We report the detection of X-ray flares from AB Dor, BO Mic, and DG CVn, while UV light curves reveal flares in both BO Mic and DG CVn.