Galactic Distribution, Radial Velocities and Masses of PN

Abstract

Since the discovery in 1779 of the first planetary nebula in the Lyra constellation by Antoine Darquier, the total number of objects known as PN has been steadily increasing. About 1600 PN have been identified in the Galaxy, although 10–20% are probably misclassified objects, which include H II regions, reflection nebulae, symbiotic stars, etc. (see for example Kohoutek, 1987; Acker et al., 1987; Stenholm and Acker, 1987).