Friday, June 23, 2023

4065 - EARLIEST STARS- may have been discovered?

 

-    4065  -  EARLIEST  STARS-  may have been discovered?   JWST may have succeeded in one of the biggest goals in the entire field of astrophysics. If this is eventually confirmed as the first true detection of a “Population III star”, it unlocks a whole new universe of scientific exploration and discovery.

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-----------   4065   -    EARLIEST  STARS-  may have been discovered?

-   The James Webb Space Telescope (JWST) may have just found the first stars in the universe.

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-    Researchers call them Population III (or Pop III) stars, because sometimes astronomers name things in reverse for some reason. Pop III are the oldest stars, Pop II are in the middle, and Pop I are the newest. Our Sun is a Pop I star.

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-    This has nothing to do with how far along a star is in its individual life cycle. Think of it more like generations.   There were two keys to this discovery. One was the simple power of JWST. Because light has a finite speed, the further away you look, the further back in time you can see

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-    The team used the telescope to spy on GN-z11, a bright, really-far-away galaxy, in the hopes of getting a strong and clear spectrum from when the universe was only about 400 million years old,   Today, it’s around 13.7 billion years old.

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-   The other is a property of starts called metallicity, the amount of metals a star has. Astronomers call anything heavier than hydrogen or helium a metal. So, in space terms, metals are just any sufficiently heavy elements.

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-   The metals contained within and burned by a star are how we categorize these celestial furnaces into their respective populations. Pop I have the highest metallicities, and Pop III have the lowest.

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-   Heavy elements, by and large, are created by stars whether it be through fusion in their inner layers or in the moments of intense heat when they go supernova. The Pop I stars currently littering the universe were made from the debris left behind when Pop II stars exploded. But Pop II stars had to get their start from older stars, as they have more metals than would have been available just after the Big Bang, but less than Pop I.

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-   If Pop II needed more metals than the Big Bang could provide, they must have been forged in Pop III stars. Pop III stars are believed to be made almost entirely of hydrogen and helium, very low metallicity.

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-    They would have been truly massive, and likely would not have lived very long  before exploding in the supernovas that researchers believe seeded the entire rest of the universe with metals.

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-    The researchers looked at the halo of gas around the outskirts of the galaxy, where they believe Pop III stars may have formed. In that region, they found a very strong HeIIλ1640 spectral line, which shows up in a spectrum when helium is extremely hot.

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-    There’s no metal around it. Not like there would usually be if there was a higher-metallicity star burning nearby. Something made helium incredibly hot without any metals present, at long last, a Pop III star.

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-    There are alternative propositions to what could have caused this HeIIλ1640 line. One of these is the potential presence of an active galactic nucleus at the center of the GN-z11 galaxy.

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-    There’s potential here.  Researchers may have succeeded in one of the biggest goals in the entire field of astrophysics. If this is eventually confirmed as the first true detection of a Population III star, it unlocks a whole new universe of scientific exploration and discovery.

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June 23,  2023        EARLIEST  STARS-  may have been discovered?           4065

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--------------------- ---  Friday, June 23, 2023  ---------------------------------

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