An analytic study of BondiHoyleLyttleton accretion. I. Stationary flows.
Abstract
We prove that the sonic surface of axisymmetric meridional stationary flows is always attached to the accretor, however small, if the adiabatic index of the gas is γ=5/3. Using local expansions near a pointlike accretor, we extend Bondi's classification of spherically symmetric flows to axisymmetric flows, introducing the possibility of angular sectors reached by no flow lines, and singular directions of infinite mass flux, in addition to the angular regions of subsonic and supersonic accretion. For γ<5/3, we show the impossibility of subsonic accretion onto a pointlike accretor when the entropy of the flow is not uniform. The special case γ=5/3 is treated separately. We analyse the influence of the adiabatic index and Mach number of the flow at infinity on the mass accretion rate of shocked spherical flows. We propose an interpolation formula for the mass accretion rate of axisymmetric flows as a function of the Mach number and the adiabatic index, in the range 9/7<γ<5/3.
 Publication:

Astronomy and Astrophysics
 Pub Date:
 April 1997
 DOI:
 10.48550/arXiv.astroph/9604160
 arXiv:
 arXiv:astroph/9604160
 Bibcode:
 1997A&A...320..342F
 Keywords:

 ACCRETION;
 ACCRETION DISKS;
 HYDRODYNAMICS;
 INSTABILITIES;
 SHOCK WAVES;
 BINARIES: CLOSE;
 XRAYS: STARS;
 Astrophysics
 EPrint:
 22 pages, A&