Abstrakt
Symbiotic stars are strongly interacting systems, in which physical mechanisms related to transfer and accretion of matter cause observable activity by manifesting increases of brightness (about 2 - 5 mag) and significant changes in their spectra. Although the brightenings of symbiotic systems have been recorded since early 20th century, many problems remain unclear until today.
These binaries consist of a cool giant of spectral type K - M and hot compact star, mostly a white dwarf. The mass transfer most likely takes place by the stellar wind of the cool giant, which is also the source of a dense circumbinary envelope of these systems.
Symbiotic systems are open binaries with orbital periods of hundreds to thousands of days and their stages of activity may last from a few days to decades. Therefore, the long-term photometric as well as spectroscopic observations of these interacting systems is needed to study the physical mechanism responsible for their observed activity.
On an example of several symbiotic systems, we will show the results of our analyzes and draw attention to open questions that remain unanswered even after more than a hundred years of observation. At the same time, we will show the important role of amateur astronomers with small telescopes in the long-term observation of symbiotic binary stars.