Echelle spectroscopy of the symbiotic star CH Cygni through quiescence.

High- and low-resolution optical spectroscopy, coupled with optical photometry, of Ch Cygni during the period from June 1986 to May 1990 is presented. The variation in Balmer line fluxes correlates with changes in emission from the hot component, and is consistent with the previously published orbital solution. Radial velocities for lines from various parts of the system are determined and compared with previous results. The origin of the double-peaked profiles of the Balmer lines is explored. Variations in radial velocity about the orbital RV curve are argued to be greater than those normally observed for isolated red giants. Observations of the forbidden O III 5007A emission line in June 1986 confirm that if this originates in the gas associated with the radio jets, the jets are moving approximately in the plane of the sky. A collimation mechanism associated with the orbital plane of the binary is inferred from this. Infrared spectroscopy in May 1990 indicates that the cool component is of the spectral type M7 or later.