Internal motions in thirty-two genuine planetary nebulae and in a misclassified object.
Abstract
The forbidden O III, H-alpha, and forbidden N II expansion velocities for thirty-three planetary nebulae are derived from high-dispersion spectroscopy. The expansion-velocity/nebular-radius correlations found by Sabbadin (1984) for planetary nebulae of the subclasses B and C of Greig (1971 and 1972) are confirmed. Observational evidence is presented indicating that A 77 (97 + 3 deg 1) is not a planetary nebula but a quite compact (nebular radius = about 1.1 pc) H II region located at about 7 kpc from the sun and excited by a late-O/early-B main-sequence star.
- Publication:
-
Astronomy and Astrophysics Supplement Series
- Pub Date:
- August 1986
- Bibcode:
- 1986A&AS...65..259S
- Keywords:
-
- Planetary Nebulae;
- Velocity Distribution;
- Astronomical Spectroscopy;
- B Stars;
- H Alpha Line;
- H Beta Line;
- H Ii Regions;
- Main Sequence Stars;
- O Stars;
- Astrophysics