The Helium Triplet Spectrum in Expanding Nebulae, II. Self-Absorption
1968; IOP Publishing; Volume: 151; Linguagem: Inglês
10.1086/149453
ISSN1538-4357
Autores Tópico(s)Stellar, planetary, and galactic studies
Resumoview Abstract Citations (137) References (10) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The Helium Triplet Spectrum in Expanding Nebulae, II. Self-Absorption Robbins, R. R. Abstract `rhe ca~pture-cascade spectrum of the helium triplets is modified to allow for self-absorption arising from the metastahility of the 23S level An integral eQuation of transfer is formulated and solved numer~ cally, in which planetary nebulae are assumed to be spheres of constant temperature and density, expand~ ing with a constant velocity gradient Line-intensity ratios as a function of Te, optical depth in X3889, and expansion rate are obtained A comparison of the solutions with observed line intensities indicates that optical depths in the helium triplets are significantly larger than the values implied by eariier studies, The expansion of the nebula contributes sigthficantly to the 1eakag~ of photor~s. Implied optical depths for observed planetary nebulae show reasonable agreement with 28S populations obtained .~rom the collisional excitation of X10830. The assumption of complete redistribution in the scattering is compared numerically with resuit~ obtained assuming a more exact scattering function due to Unno; significant differences between the two cases appear for optical dept~hs between 50 and 100 The interaction of hydrogen and helium emissions at X3889 is also investigated. Iterative methods of solving the transfer equation are considered brie~y Publication: The Astrophysical Journal Pub Date: February 1968 DOI: 10.1086/149453 Bibcode: 1968ApJ...151..511R full text sources ADS | data products SIMBAD (11) Related Materials (1) Part 1: 1968ApJ...151..497R
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