### chirp mass

**(M**_{c})
(a reduced-mass-like quantity that relates to gravitational waves)

The **chirp mass** (**M**_{c}) is a function of the masses of two
orbiting bodies that is related to the rate of energy transferred
away through gravitational waves. Its role is somewhat like reduced mass:
it encapsulates some calculation and is a relation between masses
that some observations reveal.

M_{c} = ( m_{1} m_{2} )^{3/5} / ( m_{1} + m_{2} )^{1/5}

- M
_{c} - chirp mass.
- m
_{1}, m_{2} - masses of the co-orbiting bodies.

The following differential equation approximately relates this
value to the orbit's GW frequency and its rate of change:

M_{c} = c³/G(5/96π^{-8/3}f^{-11/3}df/dt)^{3/5}

This is the equation solved for M_{c}
in terms of f and df/dt, the latter two being
the values that can be measured from observation.
(I assume the name is *chirp mass* because these two values are evident
from a GW chirp.)
It is approximate because
it is based upon the first term of a multi-term solution.
Additional information is required to solve for the individual masses.

(*physics,mass,relativity*)
http://en.wikipedia.org/wiki/Chirp_mass

**Referenced by:**

GW detection (GW)

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