Stability properties of white dwarf radiative shocks

Journal Article · Sun Sep 01 04:00:00 EDT 1985 · Astrophys. J.; (United States)

DOI:https://doi.org/10.1086/163426· OSTI ID:6337957

Imamura, J N

We study the oscillatory instability of white dwarf radiative accretion shocks discovered by Langer, Chanmugam, and Shaviv. We extend previous works by studying the properties of (1) shocks with power-law cooling functions proportional to rhoT/sup ..cap alpha../ rather than to rho/sup 2/T/sup ..cap alpha../; (2)= shocks dominated by bremsstrahlung and Compton cooling; and (3) shocks dominated by bremsstrahlung and Compton cooling when the effects of electron thermal conduction are not negligible. The results of our calculations allow us to delineate the stability regimes of white dwarf radiative shocks as a function of the dwarf mass, M/sub asterisk/, and the accretion rate, M. We parameterize M in terms of the optical depth to electron scattering through the preshock flow, tau/sub es/. In the Compton cooling and bremsstrahlung case, the shocks are unstable to low-order oscillation modes if M/sub asterisk/ < or approx. =(0.7 +- 0.1) M/sub sun/ for tau/sub es/ = 14, and if M/sub asterisk/ < or approx. =(0.9 +- 0.1)= M/sub X/ for tau/sub es/ = 1. When electron thermal conduction is added, low-order oscillation modes are unstable only if M/sub asterisk/ < or approx. =(0.3 +- 0.1) M/sub sun/. The unstable modes have approximate oscillation periods of 1.1tau/sub br/ and 0.63tau/sub br/, where tau/sub br/ is the bremsstrahlung cooling time scale of the postshock plasma. If an oscillatory instability is observed, constraints can be placed on the mass of the accreting white dwarf.

• Research Organization: Los Alamos National Laboratory
• OSTI ID: 6337957
• Journal Information: Astrophys. J.; (United States), Journal Name: Astrophys. J.; (United States) Vol. 296:1; ISSN ASJOA
• Country of Publication: United States
• Language: English

Related Subjects

640102* -- Astrophysics &amp; Cosmology-- Stars &amp; Quasi-Stellar
Radio &amp; X-Ray Sources
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
BASIC INTERACTIONS
BREMSSTRAHLUNG
COMPTON EFFECT
COOLING
DWARF STARS
EIGENFUNCTIONS
ELASTIC SCATTERING
ELECTROMAGNETIC INTERACTIONS
ELECTROMAGNETIC RADIATION
ELECTRONS
ELEMENTARY PARTICLES
ENERGY TRANSFER
FERMIONS
FLUID MECHANICS
FUNCTIONS
HEAT TRANSFER
HYDRODYNAMICS
INSTABILITY
INTERACTIONS
LEPTONS
MECHANICS
OPACITY
OPTICAL PROPERTIES
OSCILLATION MODES
OSCILLATIONS
PHYSICAL PROPERTIES
PLASMA
PLASMA INSTABILITY
PULSATIONS
RADIATIONS
RADIATIVE COOLING
SCATTERING
SHOCK WAVES
STAR ACCRETION
STAR EVOLUTION
STARS
THERMAL CONDUCTION
WHITE DWARF STARS