The symbiotic star CH Cygni - IV. Basic kinematics of the circumstellar matter during active phases

We give a brief summary of common basic characteristics of active phases during the whole (1963–2000) observed symbiotic life of CH Cygni. We identify two types of outbursts: (1) those with pronounced signatures of a high-velocity mass outflow, and (2) those displaying signatures of only a mass inflow to the central star. On the basis of the observed Hα emission, we investigate mass loss from the active star during the period from when radio jets appeared (1984.6) to the most recent activity (1998–2000). A simple expression, which relates the observed Hα luminosity to the mass-loss rate, is derived. We obtained mass-loss rates of graphic and 1.8 ± 0.7 × 10−6 M⊙ yr−1 in 1984 October, 1992 August and 1998 September, respectively. Our values are in very good agreement with radio mass-loss rates determined previously. Mass loss from CH Cygni is a transient effect connected only with active phases of type (1), and is very variable. The ejected material, which is accelerated to the same v∞ at a distance of ≈ 100 R⊙, is heavily decelerated at much larger distances (≈ 1000 au). The most recent ejecta reflect a larger deceleration.