Numerical studies of gravitational accretion from x-ray heated stellar winds

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

OSTI ID:5739629

Lupo, J A

Three numerical models of accretion from radiation driven stellar winds onto compact objects in massive x-ray binary systems are presented. The wind is given a velocity profile consistent with a radiatively driven wind, and a ''negative mass'' gravitational potential is derived from this profile to represent the wind driving force in the hydrodynamic equations. An x-ray heating model is used which determines the x-ray heating time from the Compton heating time and the known steady state energies for optically thin gas illuminated by x-rays. This allows x-ray heating to be included in the hydrodynamic equations. The x-ray luminosity is held proportional to the accretion rate, assuming that the gravitational potential energy released is equivalent to 10% of the infalling rest-mass energy. A two-dimensional Eulerian computer code is used to solve the equations of motion. Model estimates of the ionization structure, accretion rates and flow characteristics, and the effects of thermal instabilities are discussed. The impact of the x-ray radiation on the wind driving force is demonstrated. Results indicate a possible mechanism for slow x-ray flares, such as observed in 4U1700-37.

• Research Organization: New Mexico Univ., Albuquerque (USA)
• OSTI ID: 5739629
• Country of Publication: United States
• Language: English

Related Subjects

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
DIFFERENTIAL EQUATIONS
ELECTROMAGNETIC RADIATION
EQUATIONS
EQUATIONS OF MOTION
FLUID MECHANICS
GRAVITATION
HEATING
HYDRODYNAMICS
IONIZING RADIATIONS
LUMINOSITY
MATHEMATICAL MODELS
MECHANICS
OPTICAL PROPERTIES
PARTIAL DIFFERENTIAL EQUATIONS
PHYSICAL PROPERTIES
RADIATION HEATING
RADIATIONS
STAR ACCRETION
STAR EVOLUTION
STARS
STELLAR WINDS
TWO-DIMENSIONAL CALCULATIONS
VELOCITY
X RADIATION