Abstract/Details

COSMIC-RAY MODIFIED STELLAR WINDS (ACCELERATION, MODULATION, DIFFUSION, TRANSONIC SOLUTION)


1986 1986

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Abstract (summary)

A two fluid hydrodynamical model describing the modification of a stellar wind flow due to its interaction with galactic cosmic-rays is investigated. The two fluids consist of the thermal stellar wind gas and the galactic cosmic-rays. A polytropic one fluid model is used to describe the stellar wind gas, and the cosmic-rays modify the wind via their pressure gradient. The cosmic-rays are considered to be a hot low density gas of negligible mass flux, but with a significant pressure and energy flux compared to the thermal gas. The equations used are essentially those employed in two fluid hydrodynamical models of cosmic-ray shock acceleration by the first order Fermi mechanism, but suitably modified to apply in a spherical geometry and including the effects of gravity on the flow. The stellar wind consists of a transonic flow with a termination shock, and subsonic flow outside the shock. The model shows the deceleration of the wind upstream of the shock by the positive galactic cosmic-ray pressure gradient. The dissertation first discusses the fluid polytropic stellar winds and how to insert shocks in the flow. The hydrodynamical equations governing cosmic-ray modified winds are then introduced followed by a discussion of the physics of the interaction between the thermal stellar wind and the cosmic-rays. A description of the singularities of the equations is also presented. The system of equations is first solved by a finite difference method in the test particle approximation in which the cosmic-rays do not modify the flow, with appropriate boundary conditions applied at infinity, at the wind termination shock, and at the star. A perturbation scheme to determine the modification of the wind by the cosmic-rays is then developed. This scheme applies when the modification of the wind by the cosmic-rays is sufficiently small. Finally a numerical iteration is employed to exactly solve the equations. This latter method has the advantage that it can be applied when there is a considerable modification of the wind by the cosmic-rays.

Indexing (details)


Subject
Astronomy;
Astrophysics
Classification
0606: Astronomy
0606: Astrophysics
Identifier / keyword
Pure sciences
Title
COSMIC-RAY MODIFIED STELLAR WINDS (ACCELERATION, MODULATION, DIFFUSION, TRANSONIC SOLUTION)
Author
KO, CHUNG-MING
Number of pages
190
Publication year
1986
Degree date
1986
School code
0009
Source
DAI-B 47/12, Dissertation Abstracts International
Place of publication
Ann Arbor
Country of publication
United States
University/institution
The University of Arizona
University location
United States -- Arizona
Degree
Ph.D.
Source type
Dissertations & Theses
Language
English
Document type
Dissertation/Thesis
Dissertation/thesis number
8708563
ProQuest document ID
303403080
Copyright
Database copyright ProQuest LLC; ProQuest does not claim copyright in the individual underlying works.
Document URL
http://search.proquest.com/docview/303403080
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