The internal dynamics of the planetary nebulae in the Large Magellanic Cloud

The radial velocity and expansion velocity in the [O III] λ5007 line have been determined for a sample of 94 planetary nebulae (PN) in the Large Magellanic Cloud. In addition, densities and expansion velocities have been determined for a subset of 44 objects in both the Large and Small Magellanic Clouds using the [O II] λλ3727, 3729 doublet. With a few notable exceptions, the [O II] expansion velocities are well correlated with, but are systematically higher than, the [O III] expansion velocities. For a given excitation class, there appears to be an upper limit to the density, in the sense that very high density objects are always of low excitation, but low-density objects can occur at any excitation. The population of PN in the Magellanic Clouds appears to form a sheet in dynamical age/excitation class/nebular density space, and therefore represents a two-parameter family. The implication of this is that the nebular parameters are entirely determined by the properties of the central star. This fact could represent the basis of a solution to the distance scale problem for Galactic PN.