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[5.11] X-ray Variability during Optical Eclipses of a Young Binary System

K Hamaguchi, M. F. Corcoran, N. E. White (NASA/GSFC), R. Neuhauser (Jena Univ.), B. Stelzer (INAF), L. A. Balona (South African Astronomical Observatory)

We report on the XMM-Newton observations of the eclipsing binary system TY CrA, performed during the primary eclipse on 2003 March 28 for about 36 ks and the following secondary eclipse on 2003 March 29 for about 32 ks. The observations were intended to search for X-ray eclipses to identify the X-ray emitter, but we detected no X-ray eclipse in these optical eclipses. Instead, we detect a flux increase during the primary eclipse, which does not look like conventional solar-type X-ray flares and seems to coincide with the optical eclipse, while we detect no X-ray variation specific at the secondary eclipse. Surprisingly, between these two eclipses, the plasma temperature in the hot component and X-ray luminosity significantly dropped from 3.3 keV to 1.5 keV and from 1.6 \times 10³¹ ergs s^-1 to 6 \times 10³⁰ ergs s^-1, respectively. Whereas the absorption column density (N_{\rm H}) did not vary ( ~4.5 \times 10²¹ cm^-2). We discuss the origin of the X-ray emission combining results of earlier observations with ASCA, CHANDRA and XMM-Newton.

Acknowledgement: This research is supported by the National Research Council and US XMM-Newton Grant.

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Bulletin of the American Astronomical Society, 36 #2
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