- 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.
-
- 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.
-
- 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.
-
- 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.
-
- 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).
-
- 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.
-
- 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.
-
- 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.
-
- 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.
-
- 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.
-
- 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.
-
- 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.
-
- 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?
-
June 6, 2023
EARLIEST GALAXIES - ? 4039
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--------------------- --- Wednesday, June 7, 2023
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