The James Webb Space Telescope has discovered the oldest and most distant supernova ever seen – a stellar explosion that occurred when the universe was only 1.8 billion years old.
The ancient starburst was discovered among 80 others in a part of the sky that, from our perspective on Earth, is about the width of a grain of rice held at arm’s length.
Supernovae are transient objects, as their brightness changes over time. This makes the new set of distant starbursts particularly exciting, as their study could provide key insights into the unresolved questions of how the early universe grew. The researchers presented their findings on June 10 at 244th Meeting of the American Astronomical Society in Madison, Wisconsin.
“We’re essentially opening a new window into the transient universe,” Matthew Siebertan astronomer who directs spectroscopic analysis of supernovae, said in a statement. “Historically, every time we’ve done this, we’ve found incredibly exciting things — things we didn’t expect.”
There are two main categories of supernova: core collapse and runaway thermonuclear supernova.
Explosions in the first category occur when stars with masses at least eight times that of our sun run out of fuel and collapse in on themselves, before expanding outward again in a giant explosion.
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The second, known as a Type Ia supernova, occurs when two stars—one of which is the collapsed shell of a star called a white dwarf—spiral toward each other. This causes the white dwarf to peel off hydrogen from the star is spinning around, creating a runaway reaction that ends in a giant thermonuclear explosion.
Type Ia supernovae are of particular interest to astrophysicists because their explosions are thought to always have the same brightness, making them “standard candles” from which astronomers can measure distant distances and determine the rate of expansion of the universe. , known as Hubble’s constant.
But attempts to measure the Hubble constant using these standard candles and other methods have produced an alarming discrepancy—the universe appears to be expanding at different rates depending on where we look. This problem, known as the Hubble tension, has cast great doubt on the standard model of cosmology and made finding standard candles throughout the lifetime of the universe a major task for astronomers.
Researchers found the ancient supernova using data from the JWST Advanced Deep Extragalactic Survey (JADES). The survey was made by taking multiple images of the same part of the sky at one-year intervals. By looking at new points of light that appeared or faded across successive images, the researchers identified supernovae, some of which were Type Ia explosions.
Now that they have identified the explosions of extremely distant stars, researchers will study them more closely to determine their metal content and their exact distances. They say that doing so should help scientists understand the stars from which the explosions came, as well as the conditions of the “pre-teen” universe where they occurred.
“This is really our first high-redshift example [distant] the universe seems like to transient science,” Justin Pierrel, an astronomer with the JADES team, said in the statement. “We are trying to identify whether distant supernovae are fundamentally different or very similar to what we see in the nearby universe.”