This famous supernova remnant hides a secret

When massive stars reach the end of their lives and explode in supernovae, they can leave behind large structures in space called supernova remnants. It is often a favorite target of astronomers because of its beautiful and distinctive shape. They include the famous remains of SN 1987A imaged by the James Webb Space Telescope last year. Now, astronomers using Webb have taken a closer look at these remains and found something special inside.

Supernova SN 1987A was first observed in 1987 (hence its name) and was bright enough to be seen with the naked eye, making it very new by astronomical standards. Stars live for millions or even billions of years, so observing a star nearing the end of its life in real-time is a real scientific feat. When this star dies, it creates a kind of supernova called core collapse, or Type II, in which the star’s heart runs out of fuel, causing it to collapse suddenly and violently. The collapse was so severe that the material bounced off and was thrown out in an explosion reaching a quarter of the speed of light.

The James Webb Space Telescope has observed the best evidence of emission from a neutron star at the site of the famous and recently observed supernova known as SN 1987A. On the left is a NIRCam (Near Infrared Camera) image released in 2023. The image on the top right shows light from single ionized argon (Argon II) captured by the Medium Resolution Spectrograph (MRS) mode of MIRI (Mid Infrared Instrument). The image at bottom right shows light from doubly ionized argon captured by NIRSpec (Near Infrared Spectrograph). NASA, ESA, CSA, STScI, Claes Fransson (Stockholm University), Mikako Matsuura (Cardiff University), M. Barlow (UCL), Patrick Kavanagh (Maynooth University), Josefin Larsson (KTH)

This process is theorized to leave behind a small, very dense core that could be a neutron star or black hole. This theory is widely accepted, but scientists have never observed this actually happening after a supernova – until now. When the researchers turned the Webb instrument on SN 1987a, they saw evidence of a neutron star lying at the heart of the stellar remnant.

“From theoretical models of SN 1987A, the 10-second neutrino burst observed just before the supernova implies that a neutron star or black hole formed in the explosion. “But we have not observed convincing signs of such newborn objects from supernova explosions,” explained lead researcher Claes Fransson from Stockholm University in a study. statement. “With this observatory, we have now found direct evidence of emission triggered by a newborn compact object, most likely a neutron star.”

It took more than 30 years to observe the remains to find indications of the existence of a neutron star because such observations require very sensitive instruments. The remainder is one of the first objects observed by Webb when it begins science operations in July 2022 including using the Mid-Infrared Instrument (MIRI). MIRI has a special mode called Medium Resolution Spectrograph (MRS), which allows it to see ionized argon and other ionized elements produced by very high-energy photos.

“To produce the ions we observed in the ejecta, it is clear that there must be a source of high-energy radiation at the center of the SN 1987A remnant,” explains Fransson. “In this paper, we discuss various possibilities, and find that there are only a few possible scenarios, and they all involve newborn neutron stars.”

By combining evidence from MIRI with similar indications from the Near-Infrared Spectrograph (NIRSpec) instrument, researchers obtained the first direct evidence of neutron stars forming from core-collapse supernovae, bringing us one step closer to understanding the dramatic life cycles of neutron stars. star.

This research was published in the journal Science.

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