EXOSAT Observations of the Suspected Flare Star BD +48 degrees 1958A

Abstract

X-ray observations are reported for the BY Dra variable BD + 48 deg 1958A using the low-energy (LE) and the medium-energy (ME) detectors of Exosat. The star is detected in both the LE and the ME detectors, with some evidence for a long-duration (over 2-hr) X-ray flare. A combined spectral fit to the LE and ME data leads to an X-ray plasma temperature of 1.6 + or - 0.4 keV during the quiescent state and 5.0 + or - 1.4 keV during the flare. The X-ray luminosity in the 0.1-4.0 keV energy band is 2.7 x 10 to the 29th ergs/sec during the quiescent state, and a nearly 20 percent increase in the X-ray flux is detected during the flare.