South African Telescopes Contribute to Discovery of White Dwarf Pulsar

Photo Credit: Lucas Pezeta from Pexels

A new White Dwarf Pulsar has been discovered in space and South Africa’s telescopes contributed to this new discovery!

South Africa (06 July 2023) – The South African Astronomical Observatory (SAAO), the University of Cape Town (UCT) and the South African Radio Astronomy Observatory (SARAO), played a vital role in the discovery of a new White Dwarf Pulsar – Only the second discovery of its kind.

The discovery of this “pulsar” is important because it helps scientists measure their previous predictions regarding white dwarfs. In 2016, White Dwarf Pulsar “AR Scorpii” was discovered and now with the discovery of “J191213.72-441045.1 (J1912-4410 for short)”, there is a chance to test many of the theories that have been made.

One key theory looks at the “dynamo model”, which explores the strong magnetic fields of a white dwarf pulsar’s core which is said to contain dynamos (electromagnetic generators). This magnetic field is far more powerful than that of Earth. J1912-4410 spins 270 times faster than Earth, with a rotation time of just under 5 minutes. Dizzying!

“The origin of magnetic fields is a big open question in many fields of astronomy, and this is particularly true for white dwarf stars. The magnetic fields in white dwarfs can be more than a million times stronger than the magnetic field of the Sun, and the dynamo model helps to explain why. The discovery of J1912−4410 provided a critical step forward in this field”.

“We used data from a few different survey telescopes to find potential white dwarf pulsar candidates, focusing on those that had similar characteristics to AR Sco. After observing a couple of dozen candidates, we found one that showed very similar light variations to AR Sco. We then followed these up with a number of other telescopes, both from the ground and space” – Dr Ingrid Pelisoli, Research Fellow at the University of Warwick’s Department of Physics, and lead author of the discovery paper.

South African telescopes played a vital role in this. Some of the telescopes used included the optical telescopes hosted at the Sutherland site of the SAAO, including the 10-m diameter Southern African Large Telescope (SALT). Observations were also made by the MeerKAT radio telescope array.

Some interesting facts about a White Dwarf Pulsar

White dwarfs are small dense stars, typically the size of Earth.
They have a mass that is about 200,000 times greater than Earth, nearer to the mass of the Sun.
They form when a low-mass star, like the Sun, or less massive, loses its outer layers after burning all its fuel.
White dwarfs are sometimes referred to as “stellar fossils” because they offer insight into different aspects of star formation and evolution.
White dwarfs begin their lives at extremely hot temperatures before cooling down over billions of years.

You can read the detailed report by SAAO about the discovery here.

According to the website, the SAAO was founded in 1820 and is the national centre for optical and infrared astronomy in South Africa. Its primary role is to conduct fundamental research in astronomy and astrophysics by providing a world-class facility to scientists. The SAAO also promotes astronomy and astrophysics in Southern Africa by sharing research findings and discoveries and participating in outreach activities to enthuse citizens about physics and astronomy.

The Cape Town Observatory is the one people can access easily as it is found just outside the city centre. The observatory plays host to many events, and people are encouraged to visit to learn more about the research being done in South Africa.