uv and x-ray spectra of accreting degenerate dwarfs

Thesis/Dissertation · Thu Jan 01 04:00:00 EST 1981

OSTI ID:6303085

Imamura, J N

The discoveries that several degenerate dwarfs in mass transfer binary systems emit x-rays have shown that accreting degenerate dwarfs comprise an important class of celestial x-ray sources. The x-rays are produced when the accreting plasma strikes the dwarf's surface. The detailed nature of the uv and x-ray spectra due to this process must be determined by numerical integrations of the hydrodynamic and radiative transfer equations. In calculations prior to this work, researchers assumed spherically symmetric (SS) flows, that the electrons and ions in the plasma shared a common temperature and that electron thermal conduction was negligible. The calculations in this study have been refined in two ways: (1) In SS calculations, the ion and electron temperatures are allowed to differ, electron thermal conduction is included and the accreted matter is permitted to undergo steady nuclear burning. (2) The constraint of SS using a one-temperature approach is relaxed in the latter case, a magnetic field is envisioned which forces the plasma to flow along the field lines towards one or both of the dwarf's magnetic poles. It is found that two-temperature effects with electron thermal conduction can significantly alter the structure of the x-ray emitting region at the dwarf's surface. The effects are especially severe for the case where the accreted plasma burns steadily. The x-ray spectra from these structures were computed and then, using Monte Carlo techniques, the x-ray spectra observed at infinity were deduced. It is found that the consequences of the two-temperature treatment are rather slight. In general, the amount of energy in x-rays above 2 keV is increased, while the spectra are softened when compared to the one-temperature results.

• Research Organization: Indiana Univ., Indianapolis (USA)
• OSTI ID: 6303085
• Country of Publication: United States
• Language: English

Related Subjects

640102* -- Astrophysics & Cosmology-- Stars & Quasi-Stellar
Radio & X-Ray Sources
640103 -- Astrophysics & Cosmology-- Quasi-Stellar
Radio
& X-Ray Sources-- (-1987)
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
BINARY STARS
COSMIC RAY SOURCES
COSMIC X-RAY SOURCES
DATA
DWARF STARS
ELECTRON TEMPERATURE
ENERGY TRANSFER
HEAT TRANSFER
INFORMATION
ION TEMPERATURE
MAGNETIC FIELDS
MASS TRANSFER
MONTE CARLO METHOD
NUMERICAL DATA
NUMERICAL SOLUTION
PLASMA
SPECTRA
STAR ACCRETION
STAR EVOLUTION
STARS
SYMMETRY
TEMPERATURE EFFECTS
THEORETICAL DATA
THERMAL CONDUCTION
ULTRAVIOLET SPECTRA
X-RAY SPECTRA