An international team led by a physicist from the University of Sydney has identified a unique radio signal generating neutron star that rotates incredibly slowly, completing one rotation every 76 seconds.
A neutron star (blue spot at the center of the red ring) located within the remains of a supernova in the Small Magellanic Cloud, located 200,000 light years from Earth. Image Credit: NASA.
The star is unusual in that it is located in a “neutron star graveyard,” where no pulsations are expected. The MeerTRAP team used the MeerKAT radio telescope in South Africa to make the finding, which was reported in Nature Astronomy.
A single pulse was used to detect the star at first. Multiple pulses may then be confirmed using simultaneous eight-second-long photographs of the sky to validate their position.
Neutron stars are the dense leftovers of massive stellar supernova explosions. There are around 3,000 of them in the Galaxy, according to scientists. The new discovery, on the other hand, is unlike anything else that has been discovered thus far. It may belong to the theorized class of ultra-long period magnetars—stars with exceptionally powerful magnetic fields, according to scientists.
Amazingly we only detect radio emission from this source for 0.5 percent of its rotation period. This means that it is very lucky that the radio beam intersected with the Earth. It is therefore likely that there are many more of these very slowly spinning stars in the Galaxy, which has important implications for understanding how neutron stars are born and age. The majority of pulsar surveys do not search for periods this long, so we have no idea how many of these stars might exist.
Dr. Manisha Caleb, Study Lead Author, Sydney Institute for Astronomy, School of Physics, The University of Sydney
Dr. Caleb, previously of the University of Manchester, is the research lead.
PSR J0901-4046 is the name of a recently found neutron star that appears to have at least seven distinct pulse types, some of which happen at regular intervals. It has pulsar-like features, ultra-long period magnetars, and even rapid radio bursts—short flashes of radio emission in random sky locations.
This is the beginning of a new class of neutron stars. How or whether it relates to other classes is yet to be explored. There are likely many more out there. We need only look!
Dr. Manisha Caleb, Study Lead Author, Sydney Institute for Astronomy, School of Physics, The University of Sydney
The 77-member ThunderKAT team, directed by the Universities of Cape Town and Oxford, is a research partner.
The European Research Council (ERC) funded this study as part of the European Union’s Horizon 2020 research and innovation initiative (grant agreement No 694745). The South African Radio Astronomy Observatory, which is a facility of the National Research Foundation, a department of science and innovation (DSI) institution, operates the MeerKAT telescope.
The TRAPUM infrastructure, financed and deployed by the Max Planck Institut für Radioastronomie and the Max Planck Geselschaft, was used by the University of Manchester team.
Journal Reference:
Caleb, M., et al. (2022) Discovery of a radio-emitting neutron star with an ultra-long spin period of 76 s. Nature Astronomy. doi.org/10.1038/s41550-022-01688-x.