Mass-loss Rate by the Mira in the Symbiotic Binary V1016 Cygni from Raman Scattering
Authors:
Matej Sekeras, Augustin Skopal
Image & caption:
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Image caption::
Top panel shows Raman 6545Å emission (shaded area) blended with the broad Hα wing and [NII] 6548Å line. The solid line represents the observed spectrum, while dotted lines its approximation with Gaussian functions. The lower panel displays the mass-loss rate from the giant as a function of the opening angle of the neutral giant wind, θ_{R}, that defines the ionization structure of a symbiotic star in our model, and is determined by the efficiency of the Raman scattering.
Description:
The mass-loss rate from Mira variables represents a key parameter in our understanding of their evolutionary tracks. We introduce a method for determining the mass-loss rate from the Mira component in D-type symbiotic binaries via the Raman scattering on atomic hydrogen in the wind from the giant. Using our method, we investigated Raman HeII λ1025 → λ6545 conversion in the spectrum of the symbiotic Mira V1016 Cyg. We determined its efficiency to 10.2 and 14.8% and using the ionization model of symbiotic stars we determined the corresponding mass-loss rate of 2.0(+0.1/-0.2)×10^{-6} and 2.7(+0.2/-0.1)×10^{-6} solar masses per year from our spectra on 2006 April and 2007 July, respectively. Our values of the mass-loss rate that we derived from Raman scattering are comparable with those obtained independently by other methods. Applying the method to other Mira–white dwarf binary systems can aid us in modelling evolutionary tracks of the cool giants during their late stages of evolution at the asymptotic branch of the H-R diagram.
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