Abstract
Spatially resolved profiles of the He II 560 Å, H α - [N II] 6548 and 6584 Å emission lines have been obtained in two orthogonal long cuts over the Dumbbell planetary nebula. The central He II 6560 Å volume of the bright dumbbell structure is shown to be particularly inert with an expansion velocity of s-1. This is enveloped by an inner [O III] 5007 Å shell expanding at 13km s-1, an outer [O III] 5007 Å expanding at 31 km s-1 is on the inside of the outer [N II] 6584 Å shell expanding at 35 km s-1. A new H α [N II] 6548 and 6584 Å continuum-subtracted image of the 15'diameter halo has also been compared with recent proper motion measurements of the central star and the present line profiles from the halo's inner edge. Interaction with the ambient interstellar medium is suggested. The bright [N II] 6584 Å shell must be running into this relatively inert halo with a differential velocity of ≥ 25 km s-1. The present results are compared with currents models for the creation of planetary nebulae.
