A Distance Scale for Planetary Nebulae Based on Emission-Line Fluxes.
Abstract
A discussion of the distance scale and parameters of planetary nebulae is given, based on previously published and new measures of the flux in H from these objects Both the method of statistical parallaxes and the known distance of NGC 246 from the late-type companion to the exciting star are used for a calibration of the distance scale An average mass of about 0 t4 solar masses is derived. The distribution in sizes of planetary nebulae is found for a standard area and is interpreted as an evolutionary sequence in which a certain percentage of the nebulae are observed in a state in which the density is large enough that the jonized region is smaller than the volume occupied by the expanding gas Calculated distances are tabulated which should, on the average, be accurate for those objects that are optically thin and should be upper limits for those planetary nebulae that are optically thick Definite evidence for the rapid evolution of the central stars is discussed.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- March 1962
- DOI:
- 10.1086/147277
- Bibcode:
- 1962ApJ...135..371O