X and uv radiation from accreting non-magnetic degenerate dwarfs

Thesis/Dissertation · Sun Jan 01 04:00:00 EST 1978

OSTI ID:6128046

Kylafis, N D

X radiation from degenerate stars is produced by the impact of accreting matter with the stellar surface. The resulting x-ray and uv spectrum gives vital clues about the nature of the underlying star and the extreme conditions of temperature and magnetic field strength that may exist in the emission region. While the x-ray spectra of many sources have been extensively observed, the lack of systematic theoretical studies of x-ray emission from degenerate stars has so far prevented the exploitation of these observations. A comprehensive study of x-ray emission from non-magnetic degenerate dwarfs has been carried out. The results of detailed numerical calculations are reported that span the entire range of accretion rates and stellar masses, and that include the important, but previously unexplored, regime at moderate and high accretion rates. The calculations show that the characteristics of x radiation from non-magnetic degenerate dwarfs are qualitatively different than heretofore stated. It was found: (1) stars undergoing spherical accretion can produce a maximum hard x-ray luminosity L/sub h//sup max/ = 4.5 x 10/sup 36/ erg s/sup -1/, which is a factor of 4 larger, and occurs for an electron scattering optical depth more than an order of magnitude larger, than earlier estimates suggested; (2) contrary to previous reports, even high mass stars can produce low temperature (approx. less than or equal to 10 keV) x-ray spectra; (3) it has been stated that the temperature of the x-ray spectra produced by such stars is independent of x-ray intensity, and depends only on the stellar mass.

• Research Organization: Illinois Univ., Urbana (USA)
• OSTI ID: 6128046
• 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
ABSORPTION
COSMIC RAY SOURCES
COSMIC X-RAY SOURCES
DWARF STARS
LUMINOSITY
MASS
OPTICAL PROPERTIES
PHYSICAL PROPERTIES
SPECTRA
STAR ACCRETION
STAR EVOLUTION
STARS
ULTRAVIOLET SPECTRA
X-RAY SPECTRA