Wind mass transfer in S-type symbiotic binaries : III. Confirmation of a wind focusing in EG Andromedae from the nebular [OIII] lambda5007 line.
Authors:
Natalia Shagatova, Augustin Skopal, Sergey Shugarov, Richard Komzik, Emil Kundra
Image & caption:
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Image caption::
Left: Radial velocities of blue and red components of the [OIII] lambda5007 spectral line show exceptional agreement with the orbital motion of the red giant (orange line) with the shifts of -15 and +3 km/s, respectively (gray lines). This fact points to the presence of a thin environment in the vicinity of its polar regions. Right: Sketch of the circumstellar matter areas with different density and ionization structure on a cut perpendicular to the orbital plane containing the binary components.
Description:
The density distribution of the stellar wind from the red giant affects the amount of its mass transferred to the white dwarf and, subsequently, further evolution of the symbiotic binary star. In this work, we used spectra obtained at the observatories Skalnaté Pleso and Stará Lesná, as well as from the ARAS database (Astronomical Ring for Access to Spectroscopy), covering five orbital cycles of the quiet symbiotic star EG Andromedae. We analysed periodic flux and radial velocity variations of individual components of the H-alpha and [OIII] lambda5007 spectral lines. This approach revealed the asymmetric mass distribution in the orbital area, and a thin environment around the red giant poles, corresponding up to two orders of magnitude lower mass-loss rate than determined in the orbital plane. This result independently confirms that the circumstellar matter in EG Andromedae is focused towards the orbital plane of the binary. This work was included among the “Highlight“ articles in the Astronomy and Astrophysics journal (https://www.aanda.org/2021-highlights).
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