Repeated Transient Jets from a Warped Disk in the Symbiotic Prototype Z And: A Link to the Long-lasting Active Phase

Abstract

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 the high-resolution spectroscopy, multicolor U BV R 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 (∆m ≈ 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. 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.

The path to Z And-type outbursts: The case of V426 Sagittae (HBHA 1704-05)

“…Fig. 1 of Skopal et al 2018), and signatures of enhanced mass outflow (e.g. Fernández-Castro et al 1995).…”

Multiwavelength Modeling the SED of Luminous Supersoft X-Ray Sources in Large Magellanic Cloud and Small Magellanic Cloud

“…If the donor is a red giant (symbiotic binaries), the high wind-mass-transfer efficiency is achieved by the wind focusing on the orbital plane (Skopal & Cariková 2015;Shagatova et al 2016Shagatova et al , 2021. In this case, the enhanced accretion can also be sustained through the disk warping, which leads to the ejection of transient jets (Skopal et al 2018). If the accretion resumes immediately at the beginning of the post-nova SSS phase, the SSS lifetime can be substantially lengthened (Kato et al 2017).…”

Multiwavelength modeling the SED of Luminous Supersoft X-ray Sources in Large Magellanic Cloud and Small Magellanic Cloud

“…If the donor is a red giant (symbiotic binaries), the high wind-mass-transfer efficiency is achieved by the wind focusing to the orbital plane (Skopal & Cariková 2015;Shagatova et al 2016Shagatova et al , 2021. In this case, the enhanced accretion can be sustained also through the disk warping that leads to ejection of transient jets (Skopal et al 2018). If the accretion resumes immediately at the beginning of the post-nova SSS phase, the SSS lifetime can be substantially lengthened (Kato et al 2017).…”