The long-period symbiotic binary CH Cygni. I. A hundred year's history of variability.

Results are reported from a study of the visual and blue light curves of CH Cyg for the period 1885-1988. The data and analysis results are presented in extensive tables, graphs, and sample spectra and characterized in detail. It is shown that a period of inactivity from 1885 to 1963 was followed by four outburst episodes of increasing magnitude and duration, with abrupt phase-transition-like changes from inactive to high-activity periods. These features are found to be consistent with the three-step accretion model of Mikolajewski and Mikolajewska (1988), in which a magnetic-white-dwarf active component is accreting mass from the stellar wind of an M giant companion. The physical mechanisms involved in the inactive, propeller, and accretor stages of this model are explored.