- 4594 -
CARBON - abundant in early universe? The James Webb Space Telescope (JWST) has
once again found evidence that the early universe was a far more complex place
than we thought. This time, it has 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.
-
---------------------------------- 4594
- CARBON -
abundant in early universe?
-
- Earlier research suggested that carbon
started to form in large quantities relatively late, about one billion years
after the Big Bang. ‘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.
-
- But 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 chemistry.
-
- The galaxy in question, named “GS-z12”, is
thought to contain largely second generation stars, built from the remains of
those first supernovas. We were
surprised to see carbon so early in the universe, since it was thought that 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.
-
- 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.
-
- 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.
-
- 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.
-
-
October 31, 2024 CARBON -
abundent in early universe? 4594
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--------------------- --- Sunday, November 3,
2024
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