Abundances in the Crab Nebula
Abstract
The bright visual-wavelength emission lines in spectra of filaments in the Crab Nebula cannot be used to derive unique values for the relative abundances of elements there, even under a simplifying assumption that heating is due entirely to photoionization by the Crab's nonthermal continuum. However, a range of possibilities may be estimated. By mass, helium is more abundant than hydrogen; but the mass fraction of heavier elements may be surprisingly small. Such conclusions are subject to modificatioii if a noticeable fraction of the energy density involves fast particles around 1 MeV. Subject headings: abundances, nebular - Crab Nebula - supernova remnants
- Publication:
-
The Astrophysical Journal
- Pub Date:
- November 1973
- DOI:
- 10.1086/152492
- Bibcode:
- 1973ApJ...186..223D