Radio Telescope captures glitch in the Vela Pulsar.
Pulsars are rapidly rotating neutron stars and sometimes they abruptly increase their rotation rate. This sudden change of spin rate is called a “glitch” and I was part of a team that recorded one happening in the Vela Pulsar, with the results published today in Nature.
Approximately 5-6% of pulsars are known to glitch. The Vela pulsar is perhaps the most famous – a very southern object that spins about 11.2 times per second and was discovered by scientists in Australia in 1968.
It is 1,000 light-years away, its supernova occurred about 11,000 years ago and roughly once every three years this pulsar suddenly speeds up in rotation.
Read more: Fifty years ago Jocelyn Bell discovered pulsars and changed our view of the universe
These glitches are unpredictable, and one has never been observed with a radio telescope large enough to see individual pulses.
To understand what the glitch may be, first we need to understand what makes a pulsar.
Collapsing stars
At the end of a typical star’s life, one of three things can happen.
A small star, similar to the size of our Sun, will just quietly expire like a fire going out.
If the star is sufficiently large, a supernova will occur. After this massive explosion the remains will collapse. If the object is sufficiently large then its escape velocity will be greater than the speed of light, and a black hole will be formed.
But if we have a Goldilocks-sized star that is large enough to go supernova, but small enough not to be a black hole, we get a neutron star.
Read more: Explainer: why you can hear gravitational waves when things collide in the universe
The gravity is so strong that the electrons orbiting the atom are forced into the nucleus. They combine with protons in the nucleus to form neutrons.
These objects are estimated to have a mass of about 1.4 times the mass of our Sun, and a diameter of 20km. The density is such that a cupful of this material would weigh as much as Mt Everest.
They also rotate quite quickly (and very gradually slow down over time) as well as having a massive magnetic field, three trillion times that of the Earth. Electromagnetic radiation emits from both ends of this huge rotating magnet.
Now if one of the poles of this rotating magnet happens to sweep past Earth, we see a brief “flash” in radio waves (and other frequencies too) once every rotation. This is called a pulsar.
The hunt for a ‘glitch’
In 2014 I started a serious observing campaign with the University of Tasmania’s 26m radio telescope, at the Mount Pleasant Observatory, with a goal to catch the Vela Pulsar’s glitch live in action.
Tags
About the Researcher(s)
Jim Palfreyman
Mr Palfreyman has a degree in mathematics, an honours degree in computer science, a Masters in astrophysics, and his PhD in astrophysics is imminent. He has been studying the Vela pulsar for the last decade, and is a data scientist and teacher of mathematics in his spare time.
View ProfileStay Informed
Subscribe to our mailing list to receive articles direct to your inbox.