### period derivative

**(Pdot, P-dot, dP/dt)**
(rate of change in the period of an orbit or rotation)

The **period derivative** is the rate at which the period
of some cycle is changing as time passes, a period
such as an orbital period or an object's rotation period.
It is typically indicated by a P with a dot over it,
often pronounced **p-dot**:

.
P (meaning dP/dt)

Examples with astrophysical interest include period derivatives
regarding the rotation of pulsars, which gradually
slow down, a rate of use when using pulsars for timing
(e.g., for pulsar timing arrays), and period derivatives of the orbits around
compact objects, such as that of the Hulse-Taylor Binary which
demonstrated the effects of gravitational waves.

(*orbits,celestial mechanics,period,rotation*)
**Further reading:**

https://astronomy.swin.edu.au/cosmos/P/Period+Derivative

**Referenced by pages:**

P-Pdot diagram

pulsar characteristic age (τ)

Index