Relative collision probability in the
life of a star
Cumulative collision probability (normalized to 1) integrated over the
lifetime of three stellar models. The second star is assumed to
be point-like. In each case, two limiting regimes are considered.
At low relative velocities V_rel << V_ast, the collisional
cross-section scales like R_star (solid lines); at very high
velocities V_rel >> V_ast, we recover the geometrical
cross section, ~ R_star^2 (dashed lines). Stellar evolution
models are from Schaller
et al. 1992 and Meynet
et al. 1994. The evolution is only shown up to He-flash. The solid
dot shows the end of the MS phase.