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

TL;DR

This study uses AstroSat's multi-wavelength observations to analyze the magnetic activity and flares of four rapidly rotating stars, revealing their coronal and chromospheric properties.

Contribution

It provides simultaneous X-ray and UV data on active stars, offering new insights into their outer atmospheric activity and flare phenomena.

Findings

Detection of X-ray flares in three stars

UV flares observed in two stars

Coronal properties characterized for each star

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.