High Mach-number Bondi--Hoyle--Lyttleton flow around a small accretor
  In this paper, we discuss a two-dimensional numerical study of isothermal high Mach number Bondi--Hoyle--Lyttleton flow around a small accretor. The flow is found to be unstable at high Mach numbers, with the instability appearing even for a larger accretor. The instability appears to be the unstable radial mode of the accretion column predicted by earlier analytic work. 
Richard Edgar