Une étoile à neutrons (point bleu au centre de l’anneau rouge) située dans les restes d’une supernova dans le Petit Nuage de Magellan, à 200 000 années-lumière de la Terre. Crédit : ESO/NASA, ESA et l’équipe du patrimoine Hubble (STScI/AURA)/F. Vogt et al.
Début d’une nouvelle classe d’étoiles à neutrons.
Un nouveau type d’étoile à neutron star has been discovered by a University of Sydney astronomer and her colleagues in an unusual Galactic ‘graveyard’. Unlike any of its stellar neighbors, the star pulses.
An international team led by a University of Sydney scientist has discovered an unusual radio signal emitting neutron star that rotates extremely slowly, completing one rotation every 76 seconds.
Dr. Manisha Caleb. Credit: University of Sydney
The star is unique because it resides in the ‘neutron star graveyard’, where no pulsations are expected. The discovery was made by the MeerTRAP team using the MeerKAT radio telescope in South Africa and was published on May 30, 2022, in the journal Nature Astronomy.
The star was initially detected from a single pulse. It was then possible to confirm multiple pulses using simultaneous consecutive eight-second-long images of the sky, to confirm its position.
Neutron stars are extremely dense remnants of supernova explosions of massive stars. Scientists know of about 3,000 of these in our Galaxy. However, the new discovery is unlike anything seen so far. The team thinks it could belong to the theorized class of ultra-long period magnetars – stars with extremely strong magnetic fields.
“…it is very lucky that the [star’s] Le faisceau radio a croisé la Terre.”
– Dr. Manisha Caleb
Le Dr Manisha Caleb, responsable de la recherche, anciennement de l’Université de Manchester et maintenant de l’Université de Sydney, a déclaré : “Étonnamment, nous ne détectons l’émission radio de cette source que pendant 0,5 % de sa période de rotation.
“Cela signifie qu’il est très chanceux que le faisceau radio ait croisé la Terre.
“Il est donc probable qu’il y ait beaucoup plus de ces étoiles à rotation très lente dans la Galaxie, ce qui a des implications importantes pour comprendre comment les étoiles à neutrons naissent et vieillissent.
“La majorité des pulsar surveys do not search for periods this long, so we have no idea how many of these stars might exist.”
The newly discovered neutron star is named PSR J0901-4046 and seems to have at least seven different pulse types, some of which occur at regular intervals. It shows characteristics of pulsars, ultra-long period magnetars, and even fast radio bursts – brief flashes of radio emission in random locations in the sky.
“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. Caleb said.
See Strange Radio-Emitting Neutron Star Discovered in Stellar Graveyard for more on this discovery.
Reference: “Discovery of a radio-emitting neutron star with an ultra-long spin period of 76 s” by Manisha Caleb, Ian Heywood, Kaustubh Rajwade, Mateusz Malenta, Benjamin Willem Stappers, Ewan Barr, Weiwei Chen, Vincent Morello, Sotiris Sanidas, Jakob van den Eijnden, Michael Kramer, David Buckley, Jaco Brink, Sara Elisa Motta, Patrick Woudt, Patrick Weltevrede, Fabian Jankowski, Mayuresh Surnis, Sarah Buchner, Mechiel Christiaan Bezuidenhout, Laura Nicole Driessen and Rob Fender, 30 May 2022, Nature Astronomy.
DOI: 10.1038/s41550-022-01688-x
Research collaborators include the 77-person ThunderKAT team, co-led by the Universities of Cape Town and Oxford.
This research was supported by the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation program (grant agreement No 694745). The MeerKAT telescope is operated by the South African Radio Astronomy Observatory, which is a facility of the National Research Foundation, an agency of the Department of Science and Innovation (DSI). The University of Manchester team made use of the TRAPUM infrastructure, funded and installed by the Max Planck Institut für Radioastronomie and the Max Planck Geselschaft.
