Abstract
view Abstract Citations (102) References (17) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Excitation of he II in Wolf-Rayet Envelopes Castor, John I. ; van Blerkom, David Abstract We investigate the conditions of excitation which determine the strengths of the many He ii emission lines in the spectra of Wolf-Rayet stars. The observed line intensities from the WN 6 stars HD 192163 and HD 191765 are used to infer the level populations of He ii ions in their envelopes. Then, an ab initio calculation of the populations of the first thirty levels of He II is performed in which the equations of statistical equilibrium are solved with all radiative and collisional transitions included. The calculation of line transfer is based on the radial-expansion model of Wolf-Rayet envelopes, for which simplification of the transfer problem is achieved by means of an escape-probability method. The continua are treated in a similar manner, and the level populations are obtained at one representative point in the envelope. For plausihle combinations of temperature and density there is good agreement between the computed populations and those inferred from the observed line intensities. We conclude that the radialexpansion model is a valid description of the region in which He ii lines are formed. Publication: The Astrophysical Journal Pub Date: August 1970 DOI: 10.1086/150554 Bibcode: 1970ApJ...161..485C full text sources ADS |
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
