Wednesday, June 7, 2023

4039 - EARLIEST GALAXIES - what were they made of?

 

-    4039  -   EARLIEST  GALAXIES  -  what were they made of? -    The James Webb Space Telescope (JWST) has captured a stunning image of a distant barred spiral galaxy as astronomers aim to study star birth in the deeper regions of space.  JWST observed the galaxy NGC 5068, located 17 million light-years away in the constellation Virgo.


----------   4039   -   EARLIEST  GALAXIES  -  what were they made of?

-    The portrait of NGC 5068 shows tendrils of gas and stars stretching throughout the barred spiral galaxy. The bright and dense central bar of the galaxy, which sets it apart from "non-barred" spiral galaxies.

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-   These large central bars are not solid objects but are instead made of tightly clustered stars, and the stellar bars possessed by galaxies like NGC 5068 may indicate they are older and more evolved than unbarred spiral galaxies. This is because these structures are believed to take around 2 billion years to form.

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-    As this bar of stars swirls, astronomers think it may pull gas and dust to the center of these galaxies, where it acts as the fuel for intense bursts of star formation. The action of the bar in NGC 5068 seems to be causing stars to form in a spiral-like shape. These thick clouds of gas and dust that collapse to create stars also block visible light, making opaque star-forming regions difficult to study in visible light wavelengths of the electromagnetic spectrum.

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-    JWST is the ideal instrument to peer through these clouds because infrared light passes through dust and gas mostly unimpeded, and this powerful space telescope that launched on Christmas Day in 2021 is designed to see the universe in infrared.

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-    This galaxy has a diameter of at least 45,000 light-years and is seen face-on from Earth.  The two primary instruments being used are the Mid-InfraRed Instrument (MIRI) and the Near-Infrared Spectrograph (NIRSpec) both attuned to different wavelengths of infrared light.

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-    JWST has already collected images of 19 relatively nearby star-birthing galaxies, which astronomers should be able to combine with a wealth of observations from other space-based telescopes and ground-based observatories to better understand star formation.

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-    These include Hubble Space Telescope images of over 10,000-star clusters, spectroscopic mapping of around 20,000 clusters, observations of star-forming emission nebulas from the Very Large Telescope (VLT) and imaging of 12,000 dark and dense molecular clouds identified by the Atacama Large Millimeter/submillimeter Array (ALMA).

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-    Astronomers have also detected the oldest known examples of complex organic molecules in the universe.   These chemicals, much like ones found in smoke and soot on Earth, reside within an early galaxy that formed when the universe was about 10% of its current age.

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-   The carbon-based molecules, technically known as “polycyclic aromatic hydrocarbons”, are found in oil and coal deposits on Earth, as well as in smog.  These are big, floppy molecules with dozens or hundreds of atoms in them.

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-    These complex organic molecules are common in space, where they are often linked to tiny dust grains. Astronomers investigate them because they can help reveal key details of activity within galaxies.   They help influence the rate at which interstellar gas cools.

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-    Detecting these molecules in very distant galaxies that formed when the universe was relatively young has been challenging, because telescopes were limited in their sensitivity and the number of wavelengths of light they monitored.  It's remarkable that the universe can make really large, complex molecules very quickly after the Big Bang.

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-    The light the astronomers detected began its journey less than 1.5 billion years after the Big Bang.  The universe is currently about 13.8 billion years old.

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-    The discovery was made with the help of a warp in the fabric of space-time known as a gravitational lens. Albert Einstein discovered that mass distorts space-time, a bit like how a bowling ball might stretch a rubber sheet it was resting on. The greater the mass of an object, the more space-time curves around the item, and so the stronger the object's gravitational pull is.

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-     The way in which gravity behaves means that it can bend light like a lens, so a powerful gravitational field, such as that produced by a massive cluster of galaxies, can act like a giant magnifying glass.

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-     The galaxy observed by the James Webb Space Telescope shows an Einstein ring caused by a phenomenon known as lensing. Lensing occurs when two galaxies are almost perfectly aligned from our perspective on Earth. The gravity from the galaxy in the foreground causes the light from the background galaxy to be distorted and magnified, like looking through the stem of a wine glass. Because they are magnified, lensing allows astronomers to study very distant galaxies in more detail than otherwise possible.

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-    The galaxy being studied is already just as massive, and its stars have formed just as much carbon and oxygen, as our own Milky Way, even though it's only a tenth the age. It's like a third grader who's already lived an entire career, gone to college, accomplished a career's worth of work, and then retired at age eight.

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-    The new results from Webb imply that it's not actually very difficult for galaxies to produce really complex molecules through all this rich chemistry going on in space.

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-    Scientists had previously thought these complex organic molecules were linked with star formation. However, the new data revealed this might not always prove true.  They found lots of regions with these molecules but no star formation, and others with new stars forming but none of these molecules.

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-    Even more distant, younger galaxies may not have had enough time for molecules this big to form?  What was special about the regions with the molecules that allowed large molecules to form rapidly?

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June 6,  2023         EARLIEST  GALAXIES  -  ?                  4039

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--------------------- ---  Wednesday, June 7, 2023  -------------------------------

 

 

 

 

 

         

 

 

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