Abstract Title: *
Evolution of the accretion structure in the symbiotic binary BF Cyg during its last optical outburst
began in 2006

Authors: *
N. Tomov, M. Tomova

Institution: *
IA and NAO, BAS
tomov@astro.bas.bg

Oral

Abstract Text: *
The last optical eruption of the symbiotic eclipsing binary BF Cyg began in 2006 and continues
up to the present time. In 2006 its brightness rised sharply reaching a maximum and after that
gradually decreased reaching a minimum in 2014. After that it rised at two times again - in the
beginning of 2015 and 2017. Its orbital photometric minima determined by eclipses were seen
during this eruption too. In 2009 satellite components of Balmer lines indicating bipolar
collimated outflow at high velocity appeared in the spectrum. They dissapeared after 2013
entirely and appeared in 2015 again. The evolution of the accretion structure surrounding the
compact object and collimating the outflowing material is investigated on the basis of broad
band UBVRcIc photometric data and high resolution spectra taken in the range of the Balmer
lines Halpha and Hbeta. The parameters of this structure are determined at the times of the
photometric orbital minima.