Sunday, July 24, 2022

3635 - WEBB - first galaxy?

  -  3635  -  WEBB  -  first galaxy?   -  During some of the James Webb Space Telescope’s first scientific observations astrophysicists  discovered the oldest galaxy ever observed.


---------------------  3635  -    WEBB  -  first galaxy?   

-   The galaxy, “GLASS-z13“, is 13.5 billion light years away. Webb saw light from the galaxy as it looked just 300 million years after the Big Bang, when the universe was still very young.  The Universe is thought to be 13.8 billion years old.  Earth is 4.5 billion years old.

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-  The Hubble Space Telescope discovered a galaxy 13.4 billion light years away,

 “GN-Z11“.    GLASS-z13 observation smashes some assumptions about when galaxies started to form, how quickly they grew, and how many we can expect to find in the most distant reaches of the universe.

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-  Most models for the birth of the Universe predicted that such ancient galaxies would be scarce, small, and dim. But GLASS-z13 is surprisingly bright.  It is a color image of a blurry orange-white galaxy in space.

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-  Webb also discovered another surprisingly bright young galaxy, “GLASS-z11“, in the same relatively small patch of sky.  It is an area about 1.6 times wider than the full Moon viewed from Earth. 

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-  GLASS-z11 is about 13.4 billion light years away, roughly the same distance as GN-Z11. Where astronomers previously only knew of one galaxy dating back to the first few hundred million years of the universe, now they know about three. And they’ve only searched a very small area of the sky so far.

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-  That seems to defy models that predict there shouldn’t be very many bright galaxies in the oldest parts of the universe.  Computer models based on the data from Webb’s NIRCam instrument suggest that by 300 to 400 million years after the Big Bang, each galaxy had formed a collection of stars with a total mass of around 1 billion times that of our Sun. Their surprising brightness at such an early moment in the universe’s evolution has implications for just how early these galaxies began forming.

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-  The newly-discovered galaxies do match astrophysicists’ expectations by being both small compared to our own Milky Way, and to have relatively simple structures.

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-  GLASS-z13 is about 1,600 light years wide, while the slightly closer GLASS-z11 is about 2,300 light years wide. Our Milky Way galaxy is about 100,000 light years wide.  GLASS-z11 appears to be a disc-shaped galaxy, without the fancy spiral arms of galaxies like our Milky Way .

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-   That’s about what astrophysicists expected from the oldest galaxies in the universe.  How did small, simple galaxies like GLASS-z11 grow into large spiral galaxies like our Milky Way? 

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-  Astrophysicists are fairly sure that it happened in a series of cosmic collisions. The first small galaxies merged to form larger ones, and that process repeated several times and is still happening. Earlier this year, 2022, astrophysicists even found physical evidence of an ancient merger in the Large Magellanic Cloud, a small galaxy adjacent to our own.

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-  That process of galactic evolution is one of the major themes of Webb’s first year of science. Some of Webb’s first observations are focused on how the first galaxies formed and how they evolved. 

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-  Technically, GLASS-z13 and GLASS-z11 are just candidates for the title of oldest known galaxies.   More data from Webb’s instruments will help confirm whether the two galaxies really are as old as they look.

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-  Much more astronomy yet to come from the Webb telescope.

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July 23, 2022                   WEBB  -  first galaxy                            3635                                                                                                                                        

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--------------------- ---  Sunday, July 24, 2022  ---------------------------






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