TITLE:
Mass outflow from symbiotic binary BF Cygni during its current active phase

AUTHOR:
A. Shchurova

ABSTRACT:
Symbiotic stars are the class of interacting binaries with orbital periods
in order of years. They consist of a normal red giant and a white dwarf
accreting from the giant's wind. According to behavior of their long-term
optical light curves we distinguish between the so-called quiescent and
active phases. During quiescent phase, processes of mass-loss, accretion
and ionization are in mutual equilibrium. Increase in the accretion rate
can disturb this equilibrium, and lead to brightening of the system in the
optical by a few magnitudes with an increse of the mass outflow from the
hot component.
In the presentation, we demonstrate the event of outburst for the
symbiotic binary BF Cygni, which erupted during August 2006 showing a
brightening by around 1-3 magnitudes in the optical and keeps the high
level of the activity to date. We present the photometric and
spectroscopic evolution during 2015 and 2017 re-brightenings of BF Cygni.
Our observations revealed the presence of highly-collimated mass outflow
(jets) indicated in the spectrum as satellite emission components to HI
lines.