Analysis of ultraviolet resonance lines and the possible existence of coronae in O stars
A method of analyzing resonance line profiles is developed to determine the degree of ionization and the spatial distribution of ions in stellar winds. This technique is two-parameter adaptation of the Sobolev approximation for line transfer. Families of line profiles are presented for two velocity laws, several radial dependences of the ionization, and the full range of ionic abundance. These profiles can be applied to interpreting observed resonance lines of any wavelength and oscillator strength in any star through simple scaling laws. The star zeta Puppis (O4f) is analyzed in this manner to determine the ionic structure of its wind. This ionic structure is then compared to that predicted by a model consisting of a cool wind with a thin hot (Tapprox. =5 x 10/sup 6/ K) corona at the base of the flow. This model is proposed as an alternative to ''warm'' wind models, which require electron temperatures near 200,000 K, to explain the high ionization potential ions such as O/sup +5/ that are observed. Even though the coronal radiation is attenuated by the opacities of all the abundant elements, enough hard photons penetrate to produce O/sup +5/ by the Auger process throughout the stellar wind. The coronal size required to fit the observed ionic structure of zeta Pup has an emission which is very close to the X-ray upper limits set by the ANS satellite. Limits on the gas temperature and the radiation temperature in the far-UV can be obtained through this analysis.
- Research Organization:
- University of Wisconsin--Madison
- OSTI ID:
- 6502467
- Journal Information:
- Astrophys. J.; (United States), Journal Name: Astrophys. J.; (United States) Vol. 226:1; ISSN ASJOA
- Country of Publication:
- United States
- Language:
- English
Similar Records
Structure of the winds and coronae of O stars derived from H. cap alpha. line-profile analyses
Nebular observations and stellar coronae
Related Subjects
Radio & X-Ray Sources
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ABUNDANCE
ATMOSPHERES
FUNCTIONS
ION DENSITY
IONIZATION
MAIN SEQUENCE STARS
MATHEMATICAL MODELS
SPECTRA
SPECTRAL FUNCTIONS
STAR MODELS
STARS
STELLAR ATMOSPHERES
STELLAR WINDS
ULTRAVIOLET SPECTRA