The James Webb Space Telescope (JWST) has made a groundbreaking discovery, ending a nearly decade-long search for a neutron star in the aftermath of a stellar explosion. Astronomers have found a neutron star in Supernova 1987A, which is located around 170,000 light-years away in the Large Magellanic Cloud, a dwarf galaxy neighboring the Milky Way. This supernova was first observed by astronomers 37 years ago in 1987, making it the nearest and brightest supernova seen in the night sky over Earth for around 400 years.
Supernova explosions like this one are responsible for spreading elements such as carbon, oxygen, silicon, and iron throughout the cosmos. These elements become the building blocks of stars, planets, and even life itself. Neutron stars or black holes are born from these explosions, but until now, astronomers were unsure which one lurked at the heart of Supernova 1987A.
“For a long time, we’ve been searching for evidence for a neutron star in the gas and dust of Supernova 1987A,” said Mike Barlow, an emeritus professor of physics and astronomy involved in the discovery. “Finally, we have the evidence that we’ve been seeking.”
Neutron stars are formed when massive stars run out of fuel for nuclear fusion at their cores. This causes the stars to collapse under their own gravity, resulting in a tremendous supernova explosion that blasts away the outer layers. What remains is a neutron star, as wide as an average city on Earth but with a mass one or two times that of the sun. Neutron stars are composed of a dense fluid of neutron particles, making them the densest known matter in the universe.
The newly discovered neutron star in Supernova 1987A had remained hidden for 37 years due to the thick shroud of gas and dust launched during the supernova blast. This dust acted as a screen, obscuring radiation from the center of the supernova. However, the JWST’s highly sensitive infrared instruments allowed astronomers to see through this death shroud and observe emissions from the elements argon and sulfur at the heart of the supernova.
The presence of these ionized elements provided evidence of a neutron star, as only radiation emitted by a neutron star could have caused their ionization. The team determined that the brightness or luminosity of the neutron star is around a tenth of that of the sun.
While the discovery of a neutron star is significant, there are still unanswered questions. The ionization of argon and sulfur could have been caused by either winds of charged particles accelerated by a rapidly rotating neutron star or by ultraviolet and X-ray light emitted by the hot surface of the neutron star. Further observations with the JWST’s NIRSpec instrument may help distinguish between these two scenarios.
“We have a program which is gathering data now, which will be getting data with 3 or 4 times the resolution in the near-infrared,” said Barlow. “So by obtaining these new data, we may be able to distinguish the 2 models that have been proposed to explain the emission powered by a neutron star.”
This groundbreaking research was published in the journal Science and marks an important milestone in our understanding of supernovae and the birth of neutron stars. The JWST continues to push the boundaries of astronomical discovery, providing us with unprecedented insights into the mysteries of the universe.
