Scientists discover record-breaking gas cloud larger than Milky Way
Glowing in the Pegasus constellation are five seemingly tightly packed galaxies known as Stephan’s Quintet — and they whisper the secrets of galactic evolution to scientists.
like everything galaxiesthese spheres started out as masses of atomic gas that clumped together and finally collapsed on their own, forming what would become the stars that light them up. Each galaxy is made up of millions of star clusters; four are actually engaged with each other, while one is much closer together Soil.
Now, an international team of researchers using the five-hundred-meter Aperture Spherical Telescope (FAST) in China has discovered that Stephan’s Quintet is shrouded in an atomic cloud of gas 2 million light-years wide, or about 20 times the size of the Earth. Milky Way “This is the largest atomic gas structure ever found around a galaxy group,” Xu Cong, an astronomer with the National Astronomical Observatories of the Chinese Academy of Sciences and lead author of the new research, said in a statement. pronunciation (opens in new tab).
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The discovery presents a mystery and will require astronomers to rethink how gas behaves at the edges of galaxy groups, the researchers said.
Because atomic hydrogen can float more freely through galaxies than other components of an atomic gas cloud, it scatters easily when objects in a galaxy interact with each other. The scattered hydrogen in Stephan’s Quintet is a time capsule that can tell scientists about such events going back perhaps about a billion years.
The cloud is a particularly surprising find because astronomers had expected ultraviolet light to change the nature of the hydrogen in the cloud. Ultraviolet light ionizes the atoms in an atomic gas cloud that will ionize, meaning they will gain or lose electrons and eventually become charged. But the gas observed in Stephan’s Quintet is not ionized.
The lack of ionization suggests that the gas could have been left over from galactic formation. Far from any stars, diffuse clouds of atomic hydrogen still exist on their own, which could argue for the fact that they are byproducts of interactions that formed a galaxy. It’s also possible that the cloud around Stephan’s Quintet was released from an ancient crash between two of the galaxies.
While the explanation for the unified gas is still unknown, an answer could change what we think we know about how galaxies are born and continue to evolve.
The research is detailed in a paper published Oct. 19 in the journal Nature (opens in new tab).
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