The Virial Theorem is a theorem relating the kinetic and Potential Energies of a stable system as averaged over time.
2<T> = - Sum(over k=1..N) < F(k) * r(k) >
In a Gravity-bound system, this amounts to the time-averaged kinetic energy equaling the negative of the time-averaged potential energy of the objects.
The theorem helps calculation of the average total kinetic energy in complex systems.
Carbon Monoxide (CO)
Velocity Dispersion (σ)