2019MNRAS.487.2166L

We present high-resolution spectroscopy of the yellow symbiotic star AG Draconis with ESPaDOnS at the Canada-France-Hawaii Telescope. Our analysis is focused on the profiles of Raman-scattered O VI features centred at 6825 Å and 7082 Å, which are formed through Raman scattering of O VI λλ1032 and 1038 with atomic hydrogen. These features are found to exhibit double-component profiles with conspicuously enhanced red parts. Assuming that the O VI emission region constitutes part of the accretion flow around the white dwarf, Monte Carlo simulations for O VI line radiative transfer are performed to find that the overall profiles are well fitted with the accretion flow azimuthally asymmetric, with more matter on the incoming side than on the opposite side. As the mass-loss rate of the giant component is increased, we find that the flux ratio F(6825)/F(7082) of Raman 6825 and 7082 features decreases and that our observational data are consistent with a mass-loss rate {dot}M∼2 ×10^–7 M_☉ yr^–1. We also find that additional bipolar components moving away with a speed ∼70 km s^–1 provide a considerably improved fit to the red wing parts of the Raman features. The possibility that the two Raman profiles differ is briefly discussed in relation to the local variation of the O VI doublet flux ratio.