In this system, the base physical units are chosen so that the total mass, M, the gravitational constant, G, and the virial radius, R, are normalized.
The underlying assumption is that the system of N objects (stars) satisfies the virial theorem.
The consequence of standard N-body units is that the velocity dispersion of the system, v, is
The use of standard N-body units was advocated by Michel Hénon in 1971.
[1] Early adopters of this system of units included H. Cohn in 1979[2] and D. Heggie and R. Mathieu in 1986.