EG And RV and fluxes for 10 FeI lines

The selected Fe I absorption lines at 5151-6469{AA} originate at a radial distance ~1.03RG radii from its centre. The corresponding radial velocity is typically ~1km/s, which represents a few percent of the terminal velocity of the RG wind. The high scatter of the radial velocities of several km/s in the narrow layer of the stellar atmosphere points to the complex nature of the near-surface wind mass flow.

The average rotational velocity of 11km/s implies that the rotation of the donor star can contribute to observed focusing the wind towards the orbital plane. The orbital variability of the absorbed flux indicates the highest column densities of the wind in the area between the binary components, even though the absorbing neutral material is geometrically more extended from the opposite side of the giant. This wind density asymmetry in the orbital plane region can be ascribed to gravitational focusing by the white dwarf companion.

Our results suggest that both gravitational and rotational focusing contribute to the observed enhancement of the RG wind towards the orbital plane, which makes mass transfer by the stellar wind highly efficient.