HEAD Division Meeting 1999, April 1999
Session 9. Stellar Coronae
Poster, Monday, April 12, 1999, 8:30am-6:10pm, Gold Room

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[9.09] The ASCA/EUVE Campaign: Structure and Abundances of the Eclipsing Binary AR Lac

N.S. Brickhouse, A.K. Dupree, J. Sanz-Forcada (CfA), S.A. Drake, N.E. White (NASA/GSFC), K.P. Singh (Tata Inst.)

The 1.98-day eclipsing binary AR Lac (HD 210334) is a particularly important RSCVn system because it has shown evidence for extended high temperature structures as well as for compact active regions on at least one of the stars. EUVE spectra have been used to determine the shape of the AR Lac emission measure distribution, revealing a strong emission feature near 6 \times 106 K. Low metal abundances (by factors of 3 to 4) indicated by previous ASCA spectral modeling grossly change the shape and peak temperature of the radiative loss curve, and thus have strong implications for thermal stability of the corona. We report here preliminary results of our spectroscopic and light curve analyses on the simultaneous observations with ASCA and EUVE obtained in July 1997. The ASCA observations spanned 175 ks and were centered on the longer (250 ks) EUVE pointing; both primary and secondary eclipse were included in the simultaneous observing period.


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