The James Webb Space Telescope has surprised scientists by unexpectedly
detecting its first supernova, an explosion of a dying star. The detection
could possibly open up an entirely new area of research possibilities,
scientists say.
Just a few days after the start of its science operations, the James Webb
Space Telescope's NIRCam camera spotted an unexpected bright object in a
galaxy called SDSS.J141930.11+5251593, some 3 to 4 billion light-years from
Earth. The bright object dimmed over a five-day period, suggesting that it
could have been a supernova, caught by sheer luck shortly after the star
exploded. (The astronomers compared the new observations with archived data
from the Hubble Space Telescope to confirm the light was new.)
The discovery is surprising as the James Webb Space Telescope wasn't built
to search for supernovas; a task usually performed by large-scale survey
telescopes that scan vast portions of the sky at short intervals. Webb, on
the other hand, looks in great detail into a very small area of the
universe. For example, the deep field image released by U.S. President Joe
Biden in mid-July, covered an area about as large as a grain of sand.
Since the detection came already in the first week of Webb's science
operations, astronomers think that the depth of Webb's images might actually
compensate for the small area. Each deep field image includes hundreds of
galaxies — which means hundreds of opportunities to spot a supernova.
The early detection suggests the telescope might be able to see supernovas
on a regular basis, according to Inverse. That would be exciting,
particularly because Webb is expected to see the earliest galaxies that
formed in the universe, in the first hundreds of millions of years after the
Big Bang. Combine that ancient view with its unexpected supernova detection
and Webb might be able to capture the explosion of one of the
first-generation stars that lit up the universe after the dark early ages.
These stars, astronomers think, had a much simpler chemical composition than
stars that were born in later epochs.
"We think that stars in the first few million years would have been
primarily, almost entirely, hydrogen and helium, as opposed to the types of
stars we have now," Mike Engesser, an astronomer at the Space Telescope
Science Institute, which operates Webb, who led the team that announced the
detection, told Inverse. "They would have been massive — 200 to 300 times
the mass of our sun, and they would have definitely lived a sort of 'live
fast, die young' lifestyle. Seeing these types of explosions is something we
haven't really done yet."
The supernova detected marks the death of a much younger star, one only 3 to
4 billion years old, but it's a promising start for a telescope built to do
something rather different.
Supernovas are tricky to detect since the explosion itself lasts only a
fraction of a second. The bright bubble of dust and gas that these stellar
deaths generate fades after only a few days, so a telescope needs to be
looking in the right direction at the right time to catch one.
Now astronomers must hope that Webb's first supernova wasn't just beginner's
luck.
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Space & Astrophysics