Problems in radiative transfer in astrophysics: An escape probability treatment of line overlap and a model of the masers around VX Sgr
The escape probability formalism is used to treat two problems in astrophysical radiative transfer. The first problem concerns line overlap, which occurs when two or more spectral lines lie close enough together that there is a significant probability that a photon emitted in one of the lines can be absorbed in another. The second problem involved creating a detailed model of the masers around the supergiant star, VX Sgr. An escape probability procedure was developed that accounts for the effects of line overlap by integrating the amount of absorption in each of the overlapping lines. This method was used to test the accuracy of a simpler escape probability formalism developed by Elitzur and Netzer that utilized rectangular line profiles. Good agreement between the two methods was found for a wide range of physical conditions. The more accurate method was also used to examine the effects of line overlap of the far infrared lines of the OH molecule. This overlap did have important effects on the level populations and could cause maser emission. A detailed model of the OH 1612 and water masers around VX Sgr were also developed. The masers can be adequately explained using reasonable estimates for the physical parameters. It is possible to provide a tighter constraint on the highly uncertain mass loss rate from the star. Modeling the SiO masers was less successful. Their explanation will require a more exact method of treating the many levels involved and also a more accurate knowledge of the relevant physical input parameters.
- Research Organization:
- Kentucky Univ., Lexington, KY (USA)
- OSTI ID:
- 6742060
- Resource Relation:
- Other Information: Ph.D. Thesis
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
GENERAL PHYSICS
ASTROPHYSICS
ELECTRON TRANSFER
SUPERGIANT STARS
MASERS
FAR INFRARED RADIATION
PHOTONS
PROBABILITY
SPECTRA
STAR MODELS
THEORETICAL DATA
AMPLIFIERS
DATA
ELECTROMAGNETIC RADIATION
ELECTRONIC EQUIPMENT
ELEMENTARY PARTICLES
EQUIPMENT
GIANT STARS
INFORMATION
INFRARED RADIATION
MASSLESS PARTICLES
MATHEMATICAL MODELS
MICROWAVE AMPLIFIERS
MICROWAVE EQUIPMENT
NUMERICAL DATA
RADIATIONS
STARS
640102* - Astrophysics & Cosmology- Stars & Quasi-Stellar
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