X-ray activity of three rapidly rotating active stars using AstroSat

We present X-ray study of three rapidly rotating active stars namely
CC Eri, AB Dor, and FR Cnc is presented. A total of six flares are
detected on two active stars CC Eri and AB Dor. The peak X-ray
luminosities of the flares in the 0.3-7.0 keV energy band is found to
be in the range of ~1031-32 erg s-1 for all flares. Spectral analysis
indicates the presence of three and four temperature corona for CC
Eri and AB Dor, respectively, where the highest temperature and
corresponding emission meausure are found to vary along with the
flare light curve. The flare-temperatures peaked at 51 - 59 MK for the
flares observed in CC Eri and 29 - 44 MK for the flares from AB Dor.
The abundances of the flaring plasma reached up to 0.5 and 0.7
times of the solar photospheric value for CC Eri and AB Dor,
respectively. The loop-lengths for these flaring events are estimated
to be of the order of 1011cm for all flares. The energy for these flaring
events is estimated to be 1032-35 erg. FR Cnc was was in a quiescent
state during the observations and found to be rotationally modulated
with a degree of modulation of 17%. The X-ray light curve of FR Cnc
was anticorrelated with optical V-band light curve.