South Africa’s MeerKAT radio telescope is continuing to make significant new discoveries.
According to the South African Radio Astronomy Observatory (SARAO), an international team of scientists discovered a strange radio emitting neutron star, which rotates extremely slowly, completing one rotation every 76 seconds.
The team, led by members of the European Research Council-funded MeerTRAP (More Transients and Pulsars) group at the University of Manchester, says it is a unique discovery as it resides in the neutron star graveyard where scientists do not expect to see any radio emission at all.
The discovery was made using the MeerKAT radio telescope in South Africa.
This telescope, inaugurated in 2018, consists of 64 individual radio dishes that are 13.5m in diameter and distributed over an area of 8km.
MeerKAT is the most sensitive telescope of its kind in the world and is a precursor to the Square Kilometre Array (SKA) radio telescope, to be built in SA and Australia within the coming decade.
The telescope was originally known as the Karoo Array Telescope (KAT) that would consist of 20 receptors. When the South African government increased the budget to allow the building of 64 receptors, the team re-named it “MeerKAT” – “more of KAT”. The MeerKAT (scientific name Suricata suricatta) is also a small mammal that lives in the Karoo region.
Higher education, science and innovation minister Blade Nzimande recently said the MeerKAT telescope, built by South Africans, does great scientific work and will continue to do so until it is fully integrated into the SKA in the next five to seven years.
This month marked 10 years since the decision that South Africa and Australia would host the SKA, the massive international radio astronomy initiative which, on completion, will be the world’s largest radio telescope.
The total estimated cost of constructing the SKA in SA and Australia, and the associated operations and business-enabling functions, will be €2 billion (R33.6 billion) over 2021-2030.
Beams and flashes
On MeerKAT’s latest find, SARAO says the source was initially found from a single flash, or pulse, by the MeerTRAP instrument while piggybacking on imaging observations being led by a different team, ThunderKAT.
It explains that MeerTRAP and ThunderKAT then worked closely together to puzzle out its origin.
Combining the data from the two teams, it was then possible to confirm the pulsations and get an accurate position for the source, enabling detailed and more sensitive follow-up observations.
According to SARAO, neutron stars are extremely dense remnants of a supernova explosion of a massive star. It notes they can produce beams of radio waves which sweep around the sky as the neutron star spins, producing regular flashes like cosmic lighthouses.
“Scientists currently know of about 3 000 of these in our own Galaxy. However, the new discovery is unlike anything seen so far. The team think it could belong to the theorised class of ultra-long period magnetars with extremely strong magnetic fields, says SARAO.
Dr Manisha Caleb, formerly from the University of Manchester and now at the University of Sydney, who led the research says: “Amazingly, we only detect radio emission from this source for 0.5% of its rotation period. This means it is very fortuitous that the radio beam intersected with the Earth. It is, therefore, likely there are many more of these very slowly spinning sources in the Galaxy, which has important implications for how neutron stars are born and age.
“The majority of pulsar surveys do not search for periods this long and so we have no idea how many of these sources there might be. In this case, the source was bright enough that we could detect the single pulses with the MeerTRAP instrument at MeerKAT.”
SARAO points out the newly-discovered neutron star is named PSR J0901-4046, and shows characteristics of pulsars, (ultra-long period) magnetars and even fast radio bursts. While the radio energy produced suggests a pulsar origin, it adds, the pulses with chaotic sub-pulse components, and the polarisation of the pulses are reminiscent of magnetars.
Eye in the sky
Of late, the MeerKAT radio telescope has been used by scientists to make ground-breaking findings.
This, as South Africa has become one of the leaders in the field of astronomy thanks to radio telescopes like MeerKAT, HERA as well as the upcoming SKA.
“The sensitivity that MeerKAT provides, combined with the sophisticated searching that was possible with MeerTRAP and an ability to make simultaneous images of the sky, made this discovery possible,” says Dr Ian Heywood from the ThunderKAT team and the University of Oxford, who collaborated on the latest study.
“Even then it took an eagle eye to recognise it for something that was possibly a real source because it was so unusual looking.”
Using the MeerKAT radio telescope, in April, a team of researchers discovered a powerful megamaser – a radio-wavelength laser indicative of colliding galaxies.
In February, a team of astronomers made use of the radio telescope to find the most detailed images of the largest cosmic shock wave visible from earth. These gigantic shock waves are much larger than our entire galaxy and form when clusters of galaxies collide in what are the most energetic events after the Big Bang.
In January, SARAO released a new MeerKAT telescope image of the centre of our galaxy, showing radio emission from the region with unprecedented clarity and depth.
In December last year, astronomers utilised the MeerKAT to discover a mysterious chain of hydrogen gas clouds the size of a massive galaxy.
Share