Slide 2 of 59
Notes:
Pulsars (ie objects which emit radio pulses with very short periods) are isolated, highly magnetic neutron stars which radiate energy produced in the slowing down of their rapid spinning motion. Their rotational period is generally less than 1 second and the period is increasing with time.
Neutron stars are supported by degeneracy pressure because their internal densities are so high that classical gas formulae are inappropriate to describe conditions. The ‘pressure’ is a result of Heisenberg’s Uncertainty Principle and Fermi’s Exclusion Principle, which state that particles cannot occupy the same quantum state. The resultant mechanical momenta of the particles provides the pressure of the degenerate gas.
Pulsating X-ray sources, which are also known as X-ray pulsators, are compact objects (generally neutron stars) in binary systems which accrete matter from a normal star companion. The energy radiated is produced by the process of accretion and is modulated with the spin period of the neutron star. The period of X-ray pulsators is generally tens of seconds, although a few have periods of a few seconds. Their period is decreasing with time, ie. they are spinning up.
X-ray pulsators are effectively binary pulsars.
The magnetic axes of both pulsars and X-ray pulsators are not aligned with the rotation axis.