%0 Journal Article
%T Spectroscopic view on the outburst activity of the symbiotic binary AG Draconis
%A Laurits Leedj£¿rv
%A Rudolf G¨¢lis
%A Ladislav Hric
%A Jaroslav Merc
%A Maria Burmeister
%J Physics
%D 2015
%I arXiv
%X Variations of the emission lines in the spectrum of the yellow symbiotic star AG Dra have been studied for over 14 years (1997 - 2011), using more than 500 spectra obtained on the 1.5-metre telescope at Tartu Observatory, Estonia. The time interval covered includes the major (cool) outburst of AG Dra that started in 2006. Main findings can be summarized as follows: (i) cool and hot outbursts of AG Dra can be distinguished from the variations of optical emission lines; (ii) the Raman scattered emission line of O VI at $\lambda\,6825$ almost disappeared during the cool outburst; (iii) lower excitation emission lines did not change significantly during the cool outburst, but they vary in hot outbursts and also follow orbital motion; (iv) similarity of variations in AG Dra to those in the prototypical symbiotic star Z And allows to suggest that a "combination nova" model proposed for the latter object might also be responsible for the outburst behaviour of AG Dra.
%U http://arxiv.org/abs/1512.03209v1