Interpretation of the line spectrum of classical symbiotic stars in the scenario for their prototype Z And

TL;DR

This paper analyzes high-resolution spectra of the symbiotic star Z And during its 2000-2010 active phase, proposing a scenario to explain its spectroscopic phenomena and outflows, with implications for other similar stars.

Contribution

It introduces a comprehensive scenario explaining spectroscopic features and outflows in Z And during active phases, based on spectral analysis and theoretical comparisons.

Findings

Bipolar collimated outflows observed during recurrent outbursts

Differences between initial and recurrent outbursts identified

Proposed scenario explains spectral phenomena across active phases

Abstract

Results of the study of the symbiotic binary Z And during its recent active phase 2000 -- 2010 when it experienced a series of six optical outbursts are presented. High-resolution spectra obtained during the first and fourth outburst, which was the strongest one, have been analyzed. These data are compared with results of theoretical computations. The comparison provides information about the behaviour of the system during the entire active phase rather than during an individual outburst. In particular it was found fundamental difference between the first outburst, which opened the active phase, and the recurrent outbursts - namely, the presence of bipolar collimated optical outflow during some of the recurrent outbursts. A scenario that can explain all the spectroscopic phenomena observed during this active phase as well as previous active phases of Z And is proposed. The possibility to use this scenario for explanation of the line spectrum of other classical symbiotic stars during their active phases is motivated.