X-ray emission from solar neighbourhood flare stars : a comprehensivesurvey of EXOSAT results.

Abstract

Exosat Observatory observations of flare stars pertaining to 25 separate sources are examined. The Exosat instrumentation is described, and a data sample is presented. Quiescent and flaring emissions from UV Ceti-type flare stars as observed with a low-energy experiment on Exosat are discussed, and the results of the timing analysis of the low-energy data are analyzed, along with the results of the spectral analysis of the Exosat medium-energy flare data. It is observed that while all sources are detected by the low-energy experiment, the medium-energy data is limited only to large flares. It is concluded that the quiescent X-ray luminosity of different flare stars is related to the bolometric luminosity, with the quiescent X-ray emission changing little from one observation to another, and that there is a substantial variability over a different time scales, appearing in the form of either individual flares or of more gradual variations.