Expansion velocities and characteristics of galactic planetary nebulae.
Abstract
An up-to-date account of expansion data and their interpretation is provided. The importance of spatiokinematical models is underlined; bipolar outflows appear to be characteristic of very young objects and prolate spheroids (including toroids and rings) seem to be a useful approximation for many PN. High-velocity features are much more frequent than previously assumed. Expansion velocities vs. linear radii diagrams for [O III], H I, and [N II], based on a new catalogue show a broad, rather homogeneous distribution and thus are of limited value for studies of the dynamical evolution or formation mechanisms of PN - future investigations of these relations should be pursued separately for groups of PN with similar physical properties; a difference in the kinematical properties of B and C nebulae could however, be confirmed. Several recommendations for work in this area are added.
- Publication:
-
Planetary Nebulae
- Pub Date:
- 1989
- Bibcode:
- 1989IAUS..131...93W
- Keywords:
-
- Planetary Nebulae: Expansion;
- Planetary Nebulae: High-Velocity Streams