Parameters of optical variability of active galaxy nuclei

The photoelectric observations of optical variability of active galaxies nuclei are collected and analyzed. Two main components of light curves are revealed: 10-30 day short flashes and 10-30 year long waves. The corresponding mean values are determined for 16 objects. The short flashes are suggested to be a more or less random process of radiative relaxation on the scale Rsub(cont)=cxΔt. Values of Rsub(cont) derived from variability measurements are different with a high statistic significance from the values of the radius of the gas envelope of the nucleus Rsub(gas), determined from independent spectral observations. The mean value of Rsub(cont) is about 3x1016 cm and Rsub(gas) is about 1017 cm for the used set of optical data. More accurate dependences of the short-flash time on the mass and luminosity of nuclei are constructed. The observed points are grouped along the line parallel to the tidal (not gravitational) radius of the nucleus. The observed and theoretical lines can be compatible if stars in the aicinity of the active nucleus are red giants with density smaller than the solar one