2018ApJ...858..120S

Active phases of some symbiotic binaries survive for a long time, from years to decades. The accretion process onto a white dwarf (WD) sustaining long-lasting activity, and sometimes leading to collimated ejection, is not well understood. We present the repeated emergence of highly collimated outflows (jets) from the symbiotic prototype Z And during its 2008 and 2009-10 outbursts and suggest their link to the current long-lasting (from 2000) active phase. We monitored Z And with high-resolution spectroscopy, multicolor UBVR_C-and high time resolution-photometry. The well-pronounced bipolar jets were ejected again during the 2009-10 outburst together with the simultaneous emergence of the rapid photometric variability (Δm ≃ 0.06 mag) on the timescale of hours, showing similar properties as those during the 2006 outburst. These phenomena and the measured disk-jets connection could be caused by the radiation-induced warping of the inner disk due to a significant increase of the burning WD luminosity. Ejection of transient jets by Z And around outburst maxima signals a transient accretion at rates above the upper limit of the stable hydrogen burning on the WD surface, and thus proves the nature of Z And-type outbursts. The enhanced accretion through the disk warping, supplemented by the accretion from the giant's wind, can keep a high luminosity of the WD for a long time, until depletion of the disk. In this way, the jets provide a link to long-lasting active phases of Z And.