Planetary Nebula Populations and Kinematics
  The brightest planetary nebulae achieve similar maximum luminosities, have similar ratios of chemcial abundances, and apparently share similar kinematics in all galaxies. These similarities, however, are not necessarily expected theoretically and appear to hide important evolutionary differences. As predicted theoretically, metallicity appears to affect nebular kinematics, if subtly, and there is a clear variation with evolutionary stage. To the extent that it can be investigated, the internal kinematics for galactic and extragalactic planetary nebulae are similar. The extragalactic planetary nebulae for which kinematic data exist, though, probably pertain to a small range of progenitor masses, so there may still be much left to learn, particularly concerning the kinematics of planetary nebulae that descend from the more massive progenitors. 
Michael G. Richer
astro-ph.GA astro-ph.CO astro-ph.SR