PREDNASAJUCI / LECTURER :

Natalia Shagatova

NAZOV / TITLE :

Wind properties in the vicinity of the red giant in symbiotic binary EG Andromedae

ABSTRAKT / ABSTRACT :

Symbiotic stars comprise a red giant as donor of a cool and dense stellar wind,
and a hot and compact companion that is usually a white dwarf.
The hot component is powered by accretion from the giant's wind
and ionizes the fraction of surrounding medium. The process of mass
transfer in the symbiotic binaries is still not understood well.

We modelled the broadened spectral profiles of 10 Fe I absorption
lines at 5151 - 6469 Å by the semi-empirical atmosphere model for
the high-inclination symbiotic binary EG Andromedae. Previously,
the enhancement of the wind matter in the area of orbital plane
was confirmed for this system. However, the cause of this asymmetry
remained unclear. Here, we indicated additional asymmetry in the distribution
of the wind matter. The maximal absorbed fluxes measured around the superior
conjunction of the white dwarf result from a higher-density red giant wind located
in the direction towards the white dwarf. This asymmetry supports the gravitational
focusing as the mechanism responsible for the observed wind enhancement towards
the orbital plane. Also, the measured giant’s rotational velocity of 11 km/s is
sufficiently high for rotationally-induced focusing of the wind to contribute
to this pole – orbital plane density asymmetry.