Figure 6. The outer plot shows the Accretion Radius rd, normalized to the Bondi Radius RB, as a function of tB/tf, where tf is the Friction Time and tB is the time required to cross the Bondi Radius at the Encounter Velocity vrel. The smaller is the pebble; the larger is tB/tf. The inset shows pebble trajectories (black curves) with tB/tf=1, which can be compared with those of objects with tB/tf<<1 (gray curves). Clearly the accretion radius for the former is much larger. A circle of Bondi radius is plotted in red.

Source: Lambrechts and Johansen (2012).