#Eutron star definition free#

Some X-ray pulsars rotate very rapidly, with spin frequencies in excess of 400 Hz. Accretion-powered X-ray sources with strong magnetic fields usually pulse relatively slowly (some as slowly as once every 20 minutes), as the magnetic field exerts a slow-down torque on the neutron star due to the presence of ionised material. X-ray pulsars emit X-rays at regular intervals, either because of magnetospheric emission in neutron stars, or through the accretion of matter from a companion. As pulsars emit energy, their rotation frequency slows and they eventually cease radiating altogether.

#Eutron star definition free#

Radio pulsars have a вЂњ pulsar characteristic ageвЂќ which is an estimate of how old they are and an associated dispersion measure, which is dependent upon the number of free electrons between us and the pulsar. Some radio pulsars are associated with supernova remnants, and it is generally accepted that pulsars are the collapsed cores of stars that were once more massive than 6-10 times the mass of the Sun. Although the majority of pulsars spin at a rate of about once per second, the fastest pulsars can rotate at up to ~650 times a second, and anything spinning faster than around 50 milliseconds is generally referred to as a millisecond pulsar. Radio pulsars are generally accepted to be highly-magnetised, rapidly rotating neutron stars with a light-house beam of radiation that produces the pulsed emission. Hewish received the 1974 Nobel Prize in Physics for his вЂdecisive role in the discovery of pulsarsвЂ™. The first radio pulsar was discovered in 1967 by Jocelyn Bell, a graduate student from Glasgow University working with Antony Hewish at the Mullard Radio Astronomy Observatory in Cambridge.

Most of the known pulsars are only visible in the radio region of the electromagnetic spectrum and are called radio pulsars, but there is a small number of pulsars that emit at optical wavelengths, X-ray wavelengths and gamma-ray wavelengths. Bell-BurnellДЄ pulsar is an extra-terrestrial source of radiation that has a regular periodicity, usually detected in the form of short bursts of radio emission.

Jocelyn Bell (the discoverer of the first radio pulsar) with the antenna that was used.