- 3877 - GALAXY FORMATIONS - how are they born? - The Multi-Unit Spectroscopic Explorer (MUSE) instrument at the Very Large Telescope was used to study existing stars in the galaxy. It can image the galaxy in one observation with multiple wavelengths of light. At the same time, it measures the intensity of light coming from various regions. In doing so, it provides a fascinating “3D” look at the galaxy and its components.
---------- 3877 - GALAXY FORMATIONS - how are they born?
- Galaxies
fill a lot of roles in the universe. The most obvious one is star formation
factories. A galaxy classified as a
late-type spiral means it turned gas into stars more slowly in the past and
still has a lot left today.
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- The galaxy
has a massive collection of stars at its heart. In addition, it sports older
star clusters. These all indicate starforming activity in the ancient past.
There’s also ample evidence of more recent star-birth activity across the
entire galaxy. Bright nebulae highlight places where newborn stars are forming.
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- The Multi
Unit Spectroscopic Explorer (MUSE) is a second-generation instrument in
development for ESO´s Very Large Telescope (VLT). MUSE is an extremely powerful
and innovative 3D spectrograph with a wide field of view, providing
simultaneous spectra of numerous adjacent regions in the sky. The instrument is
fed by a new multiple-laser adaptive optics system on the VLT.
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- The Atacama
Large Millimeter Array provided a different view using millimeter waves (close
to radio waves). It specifically observes the clouds of hydrogen in the galaxy.
The idea is to compare the amount of gas available for star formation to the
populations of stars already formed. By using two different instruments,
astronomers get a better idea of what triggers star birth.
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- The
creation of supermassive stars can gobble up the available gas. That leaves
very little to form smaller stars. In other places, the deaths of supermassive
stars in supernova explosions send out shock waves. Those can trigger the
process of star birth in nearby molecular clouds.
-
-
Multiwavelength studies of galactic star formation to look at all
aspects of a galaxy’s structure using as many different approaches in as many
wavelengths as possible.
-
- Ultimately,
studies of galaxies like NGC 4303 and others will give a detailed understanding
of just how galaxies and their stars form and evolve. In the case of NGC 4303,
the extent of both past and future star formation looks quite impressive. The
almost uniform distribution of neutral gas clouds across its spiral arms and
core predicts a very bright future for this galaxy
-
- Staring off
into the ancient past with a $10 billion space telescope, hoping to find
extraordinarily faint signals from the earliest galaxies, might seem like a
forlorn task. But it’s only forlorn if we don’t find any. Now that the James
Webb Space Telescope has found those signals, the exercise has moved from
forlorn to hopeful.
-
- The James
Webb Space Telescope (JWST) was built to peer back in time and identify the
Universe’s very first galaxies. Those observations are meant to forge a link
between the ancient galaxies and the galaxies we see now, including our own.
That link will help astronomers understand how galaxies like ours formed and
evolved over billions of years.
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- The
expansion of the Universe stretches the light emitted by ancient objects
billions of years ago. The stretching shifts the light toward the red end of
the visible light spectrum. The James Webb Space Telescope was built to see
this light and identify the ancient galaxies that emitted it.
-
- The
telescope’s GLASS Survey used the galaxy cluster called Pandora’s Cluster
(Abell 2744) as a gravitational lens to magnify distant galaxies behind it and
found 19 bright objects that appear to be early galaxies.
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- The ESO’s
ALMA (Atacama Large Millimetre/sub-millimetre Array) was used to examine a candidate galaxy from
GLASS. There’s a tremendous difference
between the light that a distant galaxy emits and the light that arrives at our
eyes after journeying for billions of light-years across the Universe.
-
- Galaxy
named GHZ2/GLASS-z12, one of the brightest and most robust candidates at z >
10, according to the JWST observations. z > 10 means that the light from the
galaxy has been traveling for over 13.184 billion years and has traveled a
distance of at least 26.596 billion light-years.
-
- Spectroscopy
is needed to confirm the primeval nature of these candidates. It’s possible
that the light from some of these galaxies is red due to dust rather than
distance, and spectroscopy could help differentiate between the two.
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- They used
it to look for an oxygen line (O III) in the spectroscopy at the same frequency
found in the JWST observations. O III is doubly-ionized oxygen, and it’s key
because oxygen has a short formation time relative to other elements. Focusing
on oxygen increased the likelihood of detection.
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- Stars can
generate oxygen on a short 50 Million year time scale. Other elements, like
carbon, for example, take nearly 500 Myr to appear in a galaxy. This means that
oxygen is generally the best redshift indicator. Could ALMA find it?
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February
15, 2023 Galaxy Formation 3877
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--- Wednesday, February 15, 2023 ---------------------------
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