An international team of scientists, including astronomers from UK ATC in Edinburgh, have discovered the first evidence indicating the presence of a neutron star at the heart of Supernova 1987A.
Supernovae are the spectacular end result of the collapse of stars more massive than 8-10 times the mass of the Sun. Besides being the main sources of chemical elements, such as carbon, oxygen, silicon and iron, that make life possible, they are also responsible for creating the most exotic objects in the universe: neutron stars and black holes.
Supernova 1987A (SN 1987A) exploded in February 1987. Even though SN 1897A is situated in the Large Magellanic Cloud 160,000 light years from Earth it could be observed with the naked eye. Providing astronomers with an unprecedented close-up view of a supernova explosion with modern observatories.
Despite being one of the most studied objects in the sky, SN 1987A is not without its mysteries. The detection of neutrinos - tiny, elusive subatomic particles emitted during the supernova event - suggested the formation of a neutron star.
However, whether or not the neutron star persisted or collapsed into a black hole has been one of the biggest unknowns regarding SN 1987A. Even after over three and a half decades of intense monitoring with cutting-edge, world-class observatories, no conclusive evidence for the presence of a neutron star at the centre of SN 1987A has been found. Until now.
In a new study, published in the journal Science, researchers used MIRI and NIRSpec, on the James Webb Space Telescope (JWST), to observe the supernova at infrared wavelengths. They found evidence of narrow emission lines from ionised argon and sulphur atoms located at the centre of a nebula around SN 1987A. The team showed that the emission line strengths observed by JWST must be triggered by radiation from the hot neutron star or from a pulsar wind nebula around the neutron star.
Professor Claes Fransson (Stockholm University, Sweden), the lead author of the study said: “Thanks to the superb spatial resolution and excellent instruments on JWST we have for the first time been able to probe the centre of the supernova and what was created there. We now know that there is a compact source of ionising radiation, most likely by a neutron star. We have been looking for this from the time of the explosion, but had to wait for JWST to be able to verify the predictions."
Co-author Professor Gillian Wright (Director at UK ATC and Principal Investigator on MIRI) said: “JWST and MIRI are allowing us to answer some of the biggest questions in astronomy. This evidence for a neutron star in the heart of SN 1987A is a perfect example. The mission is providing new insights into our understanding of cosmic phenomena and their role in shaping the Universe as we know it."
Co-author Professor Mike Barlow (University College London) said: “Our detection with James Webb's MIRI and NIRSpec spectrometers of strong ionised argon and sulphur emission lines from the very centre of the nebula that surrounds Supernova 1987A is direct evidence of the presence of a central source of ionising radiation.
“Our data can only be fitted with a neutron star as the power source of that ionising radiation.
“This radiation can be emitted from the million degree surface of the hot neutron star, as well as by a pulsar wind nebula that could have been created if the neutron star is rapidly spinning and dragging charged particles around it.
“The mystery over whether a neutron star is hiding in the dust has lasted for more than 30 years and it is exciting that we have solved it."
Find out more.
Read the paper at Science.
