Numerical Gas-Dynamic Investigation of the Whimper Model for the Formation of Planetary Nebulae

Extract

The suggestion that the shells of planetary nebulae may be formed at the interface between two stellar winds of different velocity (“Not with a bang, but a whimper”) (Kwok, Purton and FitzGerald, 1978, Astrophys. J. 219, L 125) is investigated using the ‘beam scheme’ (Sanders and Prendergast, 1974, Astrophys. J. 188, 489) adapted to a system with spherical symmetry. Initial conditions include the remnant wind from the red giant phase and a highspeed wind from the hot nucleus ( (two tests), v = 10³km s⁻¹). The collision began at a radial distance of 200 AU. A third test at 50 AU indicated that the end result was insensitive to the details of the transition from one mass-loss mechanism to the other.