AAS 203rd Meeting, January 2004
Session 12 Eclipsing Binary Stars
Poster, Monday, January 5, 2004, 9:20am-6:30pm, Grand Hall

## [12.14] A Multi-Wavelength Study of RZ Cassiopeiae: The XMM-Newton Campaign

M. Audard (Columbia Astrophysics Laboratory), M. Güdel (Paul Scherrer Institut)

XMM-Newton and the VLA simultaneously observed the eclipsing Algol-type binary RZ Cassiopeiae in August 2003. The secondary eclipse (K3 IV companion behind the A3 V primary) was placed at the center of the 15-hour radio campaign, while the X-ray satellite monitored a full 1.2 day orbital period. We present here preliminary results of the X-ray campaign with XMM-Newton. The X-ray light curve shows significant modulation probably related to rotational modulation, and even small flares. However, the X-ray eclipse is not deep, implying that the coronal X-ray emitting material is spatially extended. The Reflection Grating Spectrometer spectrum shows a variety of bright emission lines from Fe, Ne, O, N. However, the C VI Ly\alpha line is not detected. The strong [C/N] depletion probably reflects the surface composition of the secondary which fills its Roche lobe and loses material onto the primary. The O VII He-like triplet reflects a low forbidden-to-intercombination ratio; while it generally suggests high electron densities, the ratio is here modified by photoexcitation by the strong UV flux of the primary A3 V star.

Bulletin of the American Astronomical Society, 35#5
© 2003. The American Astronomical Soceity.