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S. R. McCandliss (Johns Hopkins University), B. Espey (Trinity College Dublin), B. Frey (Johns Hopkins University)
EG And is an eclipsing symbiotic system with well determined orbital parameters, where the presence of the white dwarf has little effect on the red giant's atmosphere. This system constitutes a unique laboratory for directly measuring the temperature and chemical stratification of the giant's photospheric transition region. The cool atmosphere of the giant viewed against the hot continuum of the white dwarf produces a rich atomic and molecular absorption line spectrum, which progressively increases and then decreases as the dwarf passes in and out of eclipse. The atmospheric abundances as a function of impact parameter can then be derived from the absorption line spectroscopy for comparison to atmospheric models of cool giants.
We present highlights of FUSE Cycle 1 and 2 observations at phase points -0.21, 0.24, 0.49, 1.05, 1.07, 1.10, 1.14, and 1.21. (Zero phase is defined as where the white dwarf is totally eclipsed by the red giant.) The first three spectra define the baseline ISM absorption line systems. They also exhibit peculiar broad (FWHM~~~300~km~s-1) red-shifted (\DeltaRV~~~300~km~s-1) \ion{O}{6} and \ion{S}{6} absorption troughs at the phases -0.21 and 0.24, which turn into similarly blue-shifted (\DeltaRV~~~-300~km~s-1) absorption troughs at phase 0.49. The fourth spectrum shows only emission lines, including \ion{C}{3}, \ion{O}{3}, \ion{Si}{3}, \ion{S}{3} \ion{S}{4}, and \ion{P}{5} and an almost complete absence of white dwarf continuum. The final four spectra, taken during egress, exhibit the expected RICH and progressively declining absorption line systems, including H2, \ion{H}{1}, \ion{C}{2}, \ion{N}{1}, \ion{N}{2}, \ion{O}{1}, \ion{Ar}{1}, \ion{P}{2}, \ion{Fe}{2}, and \ion{Fe}{3}. We will discuss the current status of the data reduction effort to derive the atmospheric abundances.
This work is support by the NASA grants NAG5-8994 and NAG5-10403 to the Johns Hopkins University.
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