An EXOSAT Observation of Quiescent and Flare Coronal X-Ray Emission from Algol
Parmar, A. N.; White, N. E.; Culhane, J. L.; Kellett, B. J.; Kahn, S.; van den Oord, G. H. J.; Kuijpers, J.
Germany, United Kingdom
Abstract
X-ray emission from the Algol system is believed to originate in a corona associated with the K star. The authors have used the EXOSAT Observatory to make a 35 hr continuous observation centered on the occultation of the K star by the B star primary. The spectrum of the quiescent emission in the 1 - 10 keV band gives a temperature of 2.5×107K. This spectrum, extrapolated to lower energies, can account for more than 80% of the observed count rate. No obvious X-ray eclipse was seen. An X-ray flare was detected with a rise time of ≡1700 s and an exponential decay of ≡7000 s. The 0.1 - 10 keV peak luminosity was 1.4×1031ergs s-1. The peak temperature was 6×107K, with an iron K line confirming the thermal character of the emission.