THE GLOBAL KINEMATICS OF THE DUMBBELL PLANETARY NEBULA (NGC 6853, M27, PN G060.8-03.6)

Spatially resolved proles of the He ii 6560 A, H and [N ii] 6548 and 6584 A nebular emission lines have been obtained in two orthogonal long cuts over the Dumbbell planetary nebula. The central He ii 6560 A emitting volume of the bright dumbbell structure is shown to be particularly inert with an expansion velocity of 7 km s 1 . This is enveloped by an inner [O iii] 5007 A emitting shell expanding at 13 km s 1 , an outer [O iii] 5007 A shell expanding at 31 km s 1 which is on the inside of the outer [N ii] 6584 A emitting shell expanding at 35 km s 1 . A new H + [N ii] 6548 and 6584 A continuum-subtracted image of the 15 0 diameter halo has also been compared with recent proper motion measurements of the central star and the present line proles from the halo’s inner edge. Interaction with the ambient interstellar medium is suggested. The bright [N ii] 6584 A emitting shell must be running into this relatively inert halo with a dieren tial velocity of 25 km s 1 . The present results are compared with currents models for the creation of planetary nebulae.