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arXiv · 1512.03209

Spectroscopic view on the outburst activity of the symbiotic binary AG Draconis

Laurits Leedjärv·Rudolf Gális·Ladislav Hric·Jaroslav Merc·Maria Burmeister
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Abstract

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 $λ\,6825$ 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.

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Laurits Leedjärv, Rudolf Gális, Ladislav Hric, Jaroslav Merc, Maria Burmeister. 2015-12-10. Spectroscopic view on the outburst activity of the symbiotic binary AG Draconis. https://doi.org/10.1093/mnras%2Fstv2807

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