Binaries in a Medium of Fast LowMass Objects
Abstract
The effect of dynamical friction on binaries in a medium of fast lowmass objects is determined. Results are obtained for an arbitrary particle distribution and for any value of Eb/m(sigma squared). Heggie's Law is confirmed and made more precise. The error in the calculation of Hills (1990) is traced to the very specialized and atypical choice of phase space for performing numerical simulations. The efforts of Bekenstein and Zamir (1990) are traced to inconsistencies in their use of the Vlasov equation. It is found that both the hardening and softening terms are generated by the action of objects with speeds relative to the binary center of mass which are greater than the orbital speed. For binaries at rest with respect to isotropic distribution, this contradicts a standard result, namely, that the viscous effect of fast objects vanishes identically. This paradox is resolved by deriving a more accurate dynamical friction formula. It is shown that a term which is usually dropped is in fact the dominant one.
 Publication:

The Astrophysical Journal
 Pub Date:
 September 1991
 DOI:
 10.1086/170502
 Bibcode:
 1991ApJ...379..280G
 Keywords:

 Binary Stars;
 Particle Interactions;
 Stellar Motions;
 Viscous Drag;
 Stellar Orbits;
 Supersonic Speed;
 Viscosity;
 Astrophysics;
 STARS: BINARIES