Wind asymmetry imprint in the UV light curves of the symbiotic binary SY Mus
Authors:
N. Shagatova, A. Skopal
Image & caption:
Please click on image thumbnail to get more info:
Image caption::
Left: Model of the asymmetric ionization structure (solid red line) of SY Mus computed using the wind velocity profile derived from the observed values of the neutral hydrogen column density. Conical region around the red giant (RG) is neutral, while the rest is ionized by the radiation from the white dwarf (WD). Right: An example of the light-curve model for wavelength 1950 A.
Description:
Light curves of some symbiotic stars show an asymmetry of their descending and ascending parts. Supposing that this asymmetry is caused by an asymmetric distribution of matter originating from the stellar wind of the red giant – a companion of a white dwarf in the binary star, we modelled ultraviolet light curves of the symbiotic star SY Mus obtained from spectra of the „International Ultraviolet Explorer“ satellite for 10 wavelengths in the range from 1280 to 3080 A. We considered several scattering processes that are responsible for an attenuation of the white dwarf radiation. First, they are Rayleigh scattering on the hydrogen atoms and bound-free transitions of the negative hydrogen ions in neutral region around the red giant, and second, Thomson scattering and bound-free and free-free transitions of hydrogen atoms in ionized region around the white dwarf. It turned out that the light-curve models reproduce the observed asymmetry, and thus indicate the asymmetric distribution of the stellar wind material at the plane of observations.
SK
SAS
