Thermal instability in accretion flows onto degenerate stars

Journal Article · Wed Apr 01 04:00:00 EST 1981 · Astrophys. J., Lett. Ed.; (United States)

DOI:https://doi.org/10.1086/183514· OSTI ID:6458087

Langer, S H; Chanmugam, G; Shaviv, G

We report the discovery of a new kind of thermal instability in accretion flows onto stellar atmospheres. The instability results in periodic variations in the height of the standoff shock which forms above the stellar surface. The hard X-ray temperature and luminosity vary with this period, as does any other radiation produced in the hot gas between the shock and the surface. Conditions for the appearance of this instability are most favorable in accreting white dwarf stars, such as cataclysmic variables and AM Her stars. We suggest that a search for such variability be carried out in AM Her stars in both the hard X-ray and UN-optical bands. The resulting period, which is of order 1--100 s for AM Her stars, permits the determination of the accretion rate per unit area at the stellar surface.

• Research Organization: Joint Institute for Laboratory Astrophysics, University of Colorado and National Bureau of Standards
• OSTI ID: 6458087
• Journal Information: Astrophys. J., Lett. Ed.; (United States), Journal Name: Astrophys. J., Lett. Ed.; (United States) Vol. 245:1; ISSN AJLEA
• Country of Publication: United States
• Language: English

Related Subjects

640102* -- Astrophysics & Cosmology-- Stars & Quasi-Stellar
Radio & X-Ray Sources
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ATMOSPHERES
BINARY STARS
DWARF STARS
FLUID FLOW
FLUID MECHANICS
HYDRODYNAMICS
INSTABILITY
LUMINOSITY
MATHEMATICAL MODELS
MECHANICS
NUMERICAL SOLUTION
OPTICAL PROPERTIES
PHYSICAL PROPERTIES
SHOCK WAVES
STAR ACCRETION
STAR EVOLUTION
STAR MODELS
STARS
STELLAR ATMOSPHERES
VARIABLE STARS
VARIATIONS
WHITE DWARF STARS