The local planetary nebula (PN) census is dominated by extremely evolved, examples, and until recently, was incomplete. New discoveries from the AAO/UKST Hα Survey and SHASSA, have partially remedied this problem. In addition, we find that some currently accepted nearby PNe are in fact Strömgren spheres in the ISM ionised by a hot white dwarf. Distance estimates for a robust sample of calibrating PNe from the literature, plus new distances for a number of highly evolved PNe, have allowed a new Ha surface brightness - radius relationship to be devised as a useful distance indicator. It covers >6 dex in SB, and while the spread in SB is ∼1 dex at a given radius, optically thick (mainly bipolar and bipolar-core) PNe tend to populate the upper bound of the trend, while common-envelope PNe and very high-excitation PNe form a sharp lower boundary. Hence, distances can be estimated for all remaining local PNe, allowing the definition of a relatively complete census of PNe in the solar neighbourhood within 1.0 kpc. This provides a first look at the faint end of the PN luminosity function, and new estimates of the space density, scale height, total number, and birth rate of Galactic PNe.
|Number of pages||4|
|Journal||Proceedings of the International Astronomical Union|
|Publication status||Published - Apr 2006|
- (ISM:) planetary nebulae: general
- Stars: distances