NASA’s James Webb Space Telescope came up with the goods again. Images released by the space agency show some of the oldest galaxies ever discovered. Galaxies feature so-called stellar bars – elongated bands of stars that extend from the centers of galaxies to their outer disks like those seen in the Milky Way. Two of the six date back to a time when the universe was only 3.4 billion years old, a quarter of its current age.
One galaxy, EGS-23305, was previously imaged by the Hubble Space Telescope but the resolution wasn’t high enough for astronomers to highlight its spiral shape and prominent star bar. These fine details are clearly visible in the high-resolution image Webb produces. The structure of the second galaxy, EGS-24268, can also be clearly seen.
Both barred galaxies are about 11 billion years old, making them older than any previously discovered galaxy, and were found in data collected by Webb. Cosmic Evolution Early Publication Scientific Survey (CEERS).
Four other galaxies that were forbidden more than 8 billion years ago were also found in the data.
The co-author of the study said: “I took one look at this data, and I said, ‘We’re dropping everything else! Professor Shardha Joji, University of Texas at Austin.
“The barely visible bars in the Hubble data just appeared in the JWST image, showing the enormous power of the JWST to see through the underlying structure in galaxies.”
Stellar bars play a central role in the evolution of galaxies by transporting gas from the outer regions to the center. This gas is then rapidly converted into new stars 10 to 100 times faster than it is in the rest of the galaxy. It could also help fuel the growth of supermassive black holes found at the centers of galaxies.
Finding barred galaxies so early in the universe raises questions about current theories of galaxy evolution. The team now plans to test different models of galaxy evolution to explain their new findings.
“This discovery of early bars means that models of galaxy evolution now have a new path through the bars to accelerate the production of new stars at early ages,” Jogee said.
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