Observations of He I 31P-21S lambda 5016 and derived optical depths in six planetary nebulae.
Abstract
Spectrophotometric observations of the intensity of He I 3 1P-2 S A5Ol 6 relative to [0 iii] A5OO7 for six planetary nebulae are given. Using literature values for I(5OO7)/I(He I 4 3D-2 3P A4471), a comparison with published transfer models is made to derive optical depths in the He I singlet bound-free continuum and populations in the 1 S ground state. The singlet He0 abundance does not appear to be high enough to modify previously accepted HelH ratios. Subject headings: abundances, nebular - planetary nebulae
- Publication:
-
The Astrophysical Journal
- Pub Date:
- October 1973
- DOI:
- 10.1086/152439
- Bibcode:
- 1973ApJ...185..573B