Olga A. Tsiopa Central Astronomical Observatory of the Russian Academy of Sciences, Pulkovo
196140, St. Petersburg, Russia
Many types of stellar variability are connected with mass-loss processes.
Strong variable winds ejected by supernova precursors are revealed in early supernova
spectra, radio, and X-rays. The geometry of the circumstellar shells around the
exploding stars is surprisingly regular at different scales. The formation of shells
is a universal process for colliding winds in a series of astrophysical objects, and
is detected as a quasi-periodic variability.