Quiscent and flaring X-rays from both Gliese 867A and Gliese 867B.

Abstract

X-ray observations of the flare-star binary system Gliese 867AB obtained with the Low Energy instrument on the Exosat Observatory were analyzed. By applying a likelihood method, it is shown that both components of the system were contributing to the observed X-ray emission with an intensity ratio A:B of about 3:1. It is also shown that X-ray flares with energies of the order of 10 to the 32nd erg originated from both stars. In the light of these results, previous X-ray observations, made with the IPC instrument aboard the Einstein Observatory were reanalyzed, and it was found, somewhat unexpectedly, that during those observations G867B was roughly as bright as G867A. It was also found that the variations observed in the Einstein data were due to changes in both components, much like the flares observed with Exosat, rather than to the earlier suggestion by Agrawal (1988) of rotational modulation of G867A.