Transient jets in the symbiotic prototype Z Andromedae

TL;DR

This paper reports the observation and analysis of transient bipolar jets in the symbiotic star Z Andromedae during its 2006 outburst, revealing their properties, ejection mechanisms, and associated photometric variability.

Contribution

It provides the first detailed characterization of bipolar jets in Z And, including their collimation, ejection rates, and connection to disk disruption during outburst.

Findings

Jets appeared and disappeared during the outburst.

Jets were collimated within an average opening angle of 6.1 degrees.

Estimated total mass ejected by jets was approximately 7.4 x 10^-7 solar masses.

Abstract

We present development of the collimated bipolar jets from the symbiotic prototype Z And that appeared and disappeared during its 2006 outburst. In 2006 July Z And reached its historical maximum at U ~ 8.0. During this period, rapid photometric variations with Dm ~ 0.06 mag on the timescale of hours developed. Simultaneously, high-velocity satellite components appeared on both sides of the H-alpha and H-beta emission line profiles. They were launched asymmetrically with the red/blue velocity ratio of 1.2 - 1.3. From about mid-August they became symmetric. Their spectral properties indicated ejection of bipolar jets collimated within an average opening angle of 6.1 degrees. We estimated average outflow rate via jets to dM(jet)/dt ~ 2xE10-6(R(jet)/1AU)**(1/2) M(Sun)/year, during their August - September maximum, which corresponds to the emitting mass in jets, M(jet, emitting) ~ 6xE-10(Rjet)/1AU)^{3/2} M(Sun). During their lifetime, the jets released the total mass of M(jet, total) approx 7.4x1E-7 M(Sun). Evolution in the rapid photometric variability and asymmetric ejection of jets around the optical maximum can be explained by a disruption of the inner parts of the disk caused by radiation-induced warping of the disk.