What are closed spiral galaxies? The James Webb Space Telescope continues to revolutionize our understanding of the origins of the universe. New images from NASA in incredible detail reveal spiral galaxies with bands of stars running through their cores. The existence of such galaxies in the history of the Universe overturns the current knowledge of galaxy evolution.
Bared spiral galaxies are relatively common
Bared spiral galaxies are galaxies with spiral arms. However, unlike normal spiral galaxies, these do not emerge from the galactic core. In fact, they come from a central star bar whose extremities are the starting point of the arms.
This type of galaxy is very common in the Universe. Indeed, recent studies have shown that two out of three galaxies are barred spiral galaxies. The Milky Way is a barred spiral galaxy that contains our solar system and hundreds of billions of other systems.
As in all other spiral galaxies, each star rotates around the galactic core, causing a centrifugal force. The global rotation of the galaxy causes it to flatten and form a disk.
After its discovery, many hypotheses were put forward to explain the appearance of this star bar. The last of them emphasizes the “baby house” side of this star bar. It would act as a structure that stimulates the formation of new stars by directing gas into the central regions. This gas then turns into new stars at a rate 10 to 100 times faster than elsewhere in the galaxy. Researchers also think that this bar is only temporary (on an astronomical scale!) in the life of barred spiral galaxies. Over time, this structure eventually disappears. After that, the galaxy becomes a normal spiral galaxy.
This new discovery by James Webb is still exceptional. Still awaiting publication Astrophysical Journal, but published arXiv. The age of the barred spiral galaxies he photographed with extraordinary precision is particularly noteworthy. One of the discovered galaxies, EGS-24268, dates back to 11 billion years ago.
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A two-barred spiral galaxy 300 million years after the Big Bang
These two galaxies, EGS-23205 and EGS-24268, are the oldest barred spiral galaxies discovered by an astronomical instrument.
A few years ago, before James Webb, the Hubble telescope photographed the galaxy EGS-23205. At that time, it appeared as a disc-shaped spot. Therefore, astronomers did not know that it was a closed spiral galaxy. So we will have to wait to learn the full power of James Webb.
To enable observations of such definition, the James Webb Space Telescope has a gold mirror with 18 cells with a total diameter of 6.5 meters. This is much larger than the 2.4 meter diameter mirror of the Hubble Space Telescope. Therefore, it has the ability to collect more light. Therefore, it can see more and better solutions. Moreover, if we compare with Hubble, James Webb can pierce the galactic dust. Indeed, it operates at wavelengths ranging from 0.6 to 28 μm in the near and mid-infrared as well as the visible range.
At the same time, thanks to James Webb, astronomers from the University of Texas at Austin discovered another four barred spiral galaxies dating back to about 8 billion years ago, three billion years after the Big Bang.
The researchers also believe that the central stellar bars of barred spiral galaxies help supermassive black holes grow by channeling gas.
Also read: James Webb discovers a cluster of galaxies forming around a quasar!
Galaxy evolution models will have to be revised
Before the James Webb Telescope discovered these shots of these barred spiral galaxies, including EGS-23205 and EGS-24268, astronomers didn’t think these types of galaxies formed so early in the Universe’s history. This fantastic discovery overturns currently accepted assumptions about the evolution of galaxies. Therefore, astronomers will have to develop new theoretical models of galaxy evolution. They will then test them through simulations with the participation of supercomputers.
In the universe, the galaxy is a superstructure consisting of billions of stars and planets, interstellar dust and gas. The merger of this cluster, which can vary in size on average from 2000 to 500,000 light years, is ensured by gravitational forces. Several hundred galaxies can be bound together by the same gravitational forces. They then form galactic clusters. The latter can also merge to form galaxy superclusters such as the Serpentarius supercluster. The Virgo supercluster, also called the Local Supercluster, includes the Milky Way and the Andromeda Galaxy, among others. The diameter of this supercluster is about 200 million light years!
Also read: James Webb discovers two distant galaxies and pushes the boundaries of the Universe