- 3823
- JAMES WEBB -
sees the earliest galaxies? The James
Webb Space Telescope (JWST) has spotted
several rare red spiral galaxies, giving astronomers a new view of the early
universe. Astronomers analyzed these red
spiral galaxies in one of the first images of the galaxy cluster.
--------- 3823 - JAMES WEBB - sees the earliest galaxies?
- The researchers determined that some of
these galaxies represent the most distant spiral galaxies ever seen. The red spiral galaxies themselves aren't new
discoveries. NASA's retired Spitzer
Space Telescope imaged them in the past. But Spitzer didn't have the power of
JWST and couldn't see the details of the galaxies' shape.
-
- Called morphology, the shape of galaxies
tells the story of their evolution, so the intricate detail of these galaxies'
morphology provided by JWST could improve our understanding of the early
universe.
-
- One particular galaxy could change our
perception of the galactic population that existed during this period of cosmic
history. In the image, the astronomers spotted a red spiral galaxy in the early
universe that is "passive," or not forming stars. The discovery is
surprising, since astronomers expected galaxies in the early universe to be
actively birthing stars.
-
- Spiral galaxies are extremely common in the
cosmic neighborhood around the Milky Way, but red spiral galaxies are much
rarer, accounting for only 2% of galaxies in the local universe. The discovery
of red spiral galaxies in the early universe in observations that encompass a
relatively insignificant fraction of space suggests that these rare galaxies
were much more common in the early universe.
-
- Astronomers found that the two most
extremely red galaxies appear as they were between 8 billion and 10 billion
years ago, early in the universe's 13.8-billion-year lifespan. The two galaxies
are also the most distant and earliest known spiral galaxies to date.
-
- The fact that this is a passive galaxy that
has stopped forming stars only makes the discover more intriguing because its
existence suggests that non-star-forming galaxies could be more common in the
early universe than astronomers thought.
-
- A new analysis of distant galaxies imaged
by the James Webb Space Telescope (JWST) shows that they share characteristics
with a rare class of galaxies called "green peas" found in our cosmic
backyard. One of these galaxies, which existed when the universe was just 5% of
its current age, may be one of the most "chemically primitive"
galaxies astronomers have ever seen.
-
- "Green pea" galaxies were
discovered in observations from the Sloan Digital Sky Survey in 2009. Green
peas are so named because they stand out as small, round, unresolved dots with
a distinctly green shade. They appear green because a large fraction of light
from these rare galaxies originates from bright, glowing gas clouds that emit
light at specific wavelengths, rather than the broad spectrum of light and
continuous colors emitted by stars in other galaxies.
-
- These green pea galaxies are rare,
accounting for just 0.1% of nearby galaxies. They are also compact with
diameters of just 5,000 light-years,
just 5% the width of our galaxy, the Milky Way.
-
- Last July 2022, the JWST revealed the deepest and sharpest infrared
image of the distant universe ever taken, which captured the galaxies in and
behind a galactic cluster known as SMACS 0723.
-
- As a result of gravitational lensing,
SMACS 0723 is magnifying and distorting the appearance of the galaxies behind
it. The image revealed a trio of infrared objects that resemble the distant
relatives of local green pea galaxies.
-
- The gravitational lensing effect of SMACS
0723 magnified the most distant of these galaxies by a factor of 10, giving the
space telescope a massive natural observing boost.
-
- Using its “Near-Infrared Spectrograph”
(NIRSpec) instrument, the JWST obtained
the spectra of the galaxies in the image, which revealed the telltale signs of
oxygen, hydrogen and neon emissions, further strengthening the resemblance to
green pea galaxies.
-
- These spectrographics measure the amount of
oxygen in these distant and early galaxies for the first time, revealing that
two of these galaxies have around 20% the oxygen as the Milky Way contains.
-
- As stars die, they enrich the universe with
heavy elements that they forged during their lifetimes, meaning early galaxies
like these should be relatively deficient in elements heavier than hydrogen and
helium, which astronomers refer to as "metals," compared with older
galaxies like our own.
-
- We're seeing these objects as they existed
up to 13.1 billion years ago, when the universe was about 5% its current
age. They are young galaxies in every
sense , full of young stars and glowing gas that contains few chemical products
recycled from earlier stars.
-
- One of them contains just 2% the oxygen of a
galaxy like our own and might be the most chemically primitive galaxy yet
identified.
-
January 12, 2023 JAMES
WEBB - sees the earliest
galaxies? 3723
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--------------------- --- Friday, January 13, 2023 ---------------------------
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