- 4551 - CARBON - abundant in early galaxy? - Carbon is surprisingly abundant in an early galaxy. The James Webb Space Telescope (JWST) has once again found evidence that the early universe was a far more complex place than we thought.
----------------------------------- 4551
- CARBON -
abundant in early galaxy?
-
- This time we have detected the signature of
carbon atoms present in a galaxy that formed just 350 million years after the
Big Bang. This is one of the earliest
galaxies ever observed.
-
- Earlier research suggested that carbon
started to form in large quantities relatively late, about one billion years
after the Big Bang. But, we’ve found that carbon formed much
earlier. It might even be the oldest
metal of all.
-
- ‘Metal’ is the name astronomers give to any
element heavier than hydrogen or helium, and seeing metals like carbon so early
is a surprise. Carbon is one of the building blocks of life on Earth, but it
also plays a role in galaxy and solar system formation. It is one of the
materials that can accumulate in the protoplanetary disks around stars,
snowballing to become planets, moons, and asteroids.
-
- Astronomers weren’t expecting to see that
process happening so early. When the
first stars (called population-III stars) were born, in an era of the universe
known as “Cosmic Dawn”, the only plentiful elements around were hydrogen and
helium. All heavier elements didn’t yet exist. They were only able to form
later, inside the cores of stars, therefore wouldn’t be detectable until well
after the deaths of the first stars.
-
- Dying population-III stars that explode as
supernovas throw their heavier elements out into the universe, allowing future
populations of stars to develop rocky planets with more interesting chemistry.
-
- The galaxy in question, named “GS-z12”, is
thought to contain largely second generation stars, built from the remains of
those first supernovas. Astronomers didn’t expect the building blocks of the
galaxy to be carbon-rich.
-
- The earliest stars produced much more
oxygen than carbon. We had thought that
carbon was enriched much later, through entirely different processes, but the
fact that it appears so early tells us that the very first stars may have
operated very differently than expected.
-
- JWST’s “Near Infrared Spectrograph” allowed
astronomers to break down the light coming from the distant galaxy into its
constituent parts, revealing all the different wavelengths present. Every
element and chemical compound has its own signature when viewed via
spectroscopy, and the signal for carbon was very strong. There was also a
fainter signal for neon and oxygen, though those remain tentative detections
for the moment.
-
- How carbon emerged before oxygen is an open
question, but one hypothesis proposes that scientists now need to revisit their
models of population-III star supernovas. If these supernovas occurred with
less energy than previously thought, then they would scatter carbon from the
stars’ outer shells, while most of the oxygen present would be captured within
the event horizon as the stars collapsed into black holes.
-
- Regardless of how it happened, there is now
a strong case for heavy elements early in the universe. JWST is revealing unexpected details about
the first galaxies that will ultimately make scientists’ predictions about the
evolution of the universe.
-
- These observations tell us that carbon can
be enriched quickly in the early universe.
And, because carbon is fundamental to life as we know it, it’s not
necessarily true that life must have evolved much later in the universe.
Perhaps life emerged much earlier.
Although if there’s life elsewhere in the universe, it might have
evolved very differently than it did here on Earth.
-
-
September 9, 2024 CARBON
- abundant in early galaxy? 4551
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--------------------- --- Monday, September 9,
2024
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