Simple definition of Bondi Radius Can anyone help me by defining what is exactly Bondi Radius? I have searched far and wide but the results are very complicated and so far I have only rough idea of it but I just cant explain it very well
From the mysterious site Vaporia, which is a fantastic index for astrophysics terms (and other things I'm seeing now): 


  The Bondi radius is analogous to the Hill radius, both giving an idea
  of how far from an object, a medium (gas, dust) is likely to be drawn
  in and accreted. The Bondi radius takes into account the (relative)
  speed of the object through the medium, and the medium's density and
  sound-speed. Accretion due to material falling within the Bondi radius
  is called Bondi accretion. 


Try to picture a heavy object, perhaps a planet, travelling through a gaseous or dusty medium. Now, some of the gas is eventually going to be the victim of accretion to the planet. The planet is going to pull gas/dust from the medium and the Bondi radius tells you how far from the planet gas/dust is likely to be accreted to the planet. 

Hopefully this is more clear!