The symbiotic system AG Draconis. Soft X-ray bremsstrahlung from the nebulae
arXiv:1009.3209 · doi:10.1016/j.newast.2010.08.006
Abstract
The modeling of UV and optical spectra emitted from the symbiotic system AG Draconis, adopting collision of the winds, predicts soft X-ray bremsstrahlung from nebulae downstream of the reverse shock with velocities > 150 km/s and intensities comparable to those of the white dwarf black body flux. At outbursts, the envelop of debris, which corresponds to the nebula downstream of the high velocity shocks (700-1000 km/s) accompanying the blast wave, absorbs the black body soft X-ray flux from the white dwarf, explains the broad component of the H and He lines, and leads to low optical-UV-X-ray continuum fluxes. The high optical-UV flux observed at the outbursts is explained by bremsstrahlung downstream of the reverse shock between the stars. The depletion of C, N, O, and Mg relative to H indicates that they are trapped into dust grains and/or into diatomic molecules, suggesting that the collision of the wind from the white dwarf with the dusty shells, ejected from the red giant with about 1 year periodicity, leads to the U-band fluctuations during the major bursts.
12 pages, 5 figures, 2 tables. New Astronomy, in press
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