- Jonathan Amos
- science correspondent
It’s like a pearl necklace.
This is an image of a supernova (exploded star) taken by the new James Webb Superspace Telescope (JWST).
SN1987A, as it is known, is one of the most famous and studied objects in the Southern Hemisphere sky.
When the star went boom in 1987, it was the closest and brightest supernova seen from Earth in almost 400 years. And now the $10bn (£8bn) Webb Observatory is showing us details never before revealed.
SN1987A is located in the Large Magellanic Cloud, a dwarf galaxy adjacent to our Milky Way galaxy, just 170,000 light-years away from us.
Astronomers are fascinated by this object because it allows us to observe the complexities of what happens to large stars as they reach the end of their lives.
A series of bright rings represent bands of gas and dust ejected by stars in various stages of death, then excited and illuminated by expanding shock waves emitted in the final moments of their collapse and explosion. .
Scientists calculate that one of these rings is a string of pearls made up of material ejected about 20,000 years before the last event.
The web provides the clearest view ever of the necklace and the diffused light around it. Webb also spotted a pearl-like addition, or two, that weren’t present in previous images such as those from the Hubble Space Telescope (see image below).
Dr. Roger Wesson from Cardiff University in the UK explained, “We have confirmed that a new hot spot has appeared outside the previously irradiated ring.”
“We also observed light emission from hydrogen molecules within the ring, which was not necessarily expected and could only be uncovered by JWST, which has excellent sensitivity and resolution,” he said. told BBC News.
Another new feature is a crescent moon or arc of luminescence on the inside of the necklace, but just outside the dense interior area that looks like a keyhole.
“We still don’t understand much about Mikazuki,” said Dr. Mikako Matsuura, who led the latest analysis.
“This material could be glowing due to some kind of back-impact, an impact that bounces back toward the keyhole.”
What Webb can’t see are the remnants of the star. It is buried somewhere in a dense dust field that is a keyhole.
The debris should be a very compact object, consisting entirely of neutron particles and only a few tens of kilometers in diameter.
For the past 36 years, all large telescopes capable of viewing SN1987A have studied its evolving shape and features.
At the heart of these investigations is the question of why supernovae occur in the first place.
Astronomers believe that its ancestor was a hot, relatively young star, perhaps 20 to 30 times more massive than the Sun. It was certainly large enough to cause an explosion, but it wasn’t at that stage yet.
“One of the mysteries of this star is that the theory at the time was that only red supergiants could explode, but this star exploded as a blue supergiant. Therefore, it is difficult to solve this mystery. “It was one of the great quests,” Dr. Wesson said.
“The Webb is likely to remain in service for much longer than originally anticipated, perhaps 20 years. It gives you the tools.”
The images at the top of this page are from Webb’s main camera, the Near Infrared Camera, or NIRCam. When combined with the telescope’s 6.5-meter-wide primary mirror and associated optics, it produces stunning photographs.
But Webb’s secret weapon is a suite of spectrometers, devices that split the light emitted by an object into its component colors. This reveals the chemistry, temperature, density, and velocity of the target being studied.
Observations of SN1987A using Webb’s near-infrared spectrometer (NIRSpec) will be included in a forthcoming report. This is expected to include further exciting revelations about this remarkable supernova.
James Webb is a joint project of the U.S., European, and Canadian space agencies. It was launched in December 2021 and is considered the successor to the Hubble Space Telescope.