An Etymological Dictionary of Astronomy and Astrophysics

In the → Bondi-Hoyle accretion process, the radius where the gravitational energy owing to star is larger than the kinetic energy and, therefore,
at which material is bound to star. The Bondi-Hoyle accretion radius is given by

R_BH = 2 GM / (v² + c_s²)

where G is the gravitational constant, M is the stellar mass, v the gas/star relative velocity, and c_s is the sound speed.

See also: → Bondi-Hoyle accretion; → radius.