Wind mass transfer in S-type symbiotic binaries: II. Indication of wind focusing.
Authors:
N. Shagatova, A. Skopal, Z. Carikova
Image & caption:
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Image caption::
Left: Measured values of the column densities of neutral hydrogen around the cool giant in the symbiotic binary EG And (full circles) and their model (solid line). Right: Corresponding velocity profiles of the wind for different orbital inclinations. These results imply high values of the mass-loss rate via the wind from the giant that indicates its focusing towards the orbital plane.
Description:
In symbiotic stars, the stellar wind from the cool giant companion is transferred onto the white dwarf (WD). However, high luminosities of WDs in symbiotic stars cannot be generated by a standard accretion from the stellar wind. In our paper, we investigated this problem for the eclipsing symbiotic binaries EG And and SY Mus. By modelling their archival ultraviolet spectra around the Ly-alpha line by Rayleigh scattering we determined column densities of neutral hydrogen around the cool giants. Solving the inversion problem for the column density function, we determined the velocity field of the wind at the near-orbital-plane region, corresponding densities and the mass-loss rate from the giant. However, our values of mass-loss rates were a factor of > 10 higher than those obtained by other methods. This result indicates a focusing of the giant's wind towards the orbital plane, where it can be accreted by the WD at a very high rate. Our findings allow us to understand better the nature of the high luminosity of WD.
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