A “totally new phenomenon” has been discovered by astronomers in a strange galaxy from the dawn of time.
This galaxy, named GS-NDG-9422 (9422), was discovered by the James Webb Space Telescope to have an unusual light signature suggesting that its gas shines brighter than its stars, according to a new paper in the journal Monthly Notices of the Royal Astronomical Society.
This galaxy existed about 1 billion years after the Big Bang—which occurred about 13.8 billion years ago—meaning that it could be a missing link between the formation of the universe’s earliest galaxies and the galaxies that exist today.
The galaxy GS-NDG-9422 as captured by the James Webb Space Telescope NIRCam (Near-Infrared Camera). The light we see in this image is coming from the galaxy’s hot gas, rather than its stars.
NASA, ESA, CSA, STScI, Alex Cameron Oxford
“My first thought in looking at the galaxy’s spectrum was, ‘that’s weird,’ which is exactly what the Webb telescope was designed to reveal: totally new phenomena in the early universe that will help us understand how the cosmic story began,” study co-author Alex Cameron, a researcher at the University of Oxford, said in a statement.
The researchers modeled the bizarre light signature from the newly discovered ancient galaxy, and found that it could be explained by the gas clouds in the galaxy being heated to immense temperatures by extremely hot stars, so much so that the gas actually shone more brightly than the stars themselves. Therefore, the images of the galaxy taken by the James Webb Space Telescope are actually lit up by this hot gas, rather than the stars.
“It looks like these stars must be much hotter and more massive than what we see in the local Universe, which makes sense because the early Universe was a very different environment,” study co-author Harley Katz, a researcher at the University of Oxford and the University of Chicago, said in the statement.
Galaxy 9422’s stars appear to be burning at 140,000 degrees Fahrenheit, which is much higher than the average temperature of stars in the universe today, which ranges between 70,000 to 90,000 degrees F.
Webb observations of galaxy GS-NDG-9422 (top) and a comparions of what astronomers would expect to see in a “typical” galaxy (bottom), with its light coming predominantly from stars (white line), with a theoretical model of light coming from hot nebular gas, outshining stars (yellow line). The unusual downturn of the galaxy’s spectrum, leading to an exaggerated spike in neutral hydrogen, is nearly a perfect match to Katz’s model of a spectrum dominated by super-heated gas.
NASA, ESA, CSA, Leah Hustak STScI
The galaxy is thought to be forming many of these huge, hot stars within clouds of gas, causing the gas to shine incredibly brightly. This may show how some of the first generation of stars formed, which are called Population III stars.
“We know that this galaxy does not have Population III stars, because the Webb data shows too much chemical complexity. However, its stars are different than what we are familiar with—the exotic stars in this galaxy could be a guide for understanding how galaxies transitioned from primordial stars to the types of galaxies we already know,” said Katz.
The researchers hope to use the JWST to find more galaxies from the earliest days of the universe to further understand how the first stars and galaxies formed.
“It’s a very exciting time, to be able to use the Webb telescope to explore this time in the Universe that was once inaccessible,” Cameron said. “We are just at the beginning of new discoveries and understanding.”
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References
Cameron, A. J., Katz, H., Witten, C., Saxena, A., Laporte, N., & Bunker, A. J. (2024). Nebular dominated galaxies: insights into the stellar initial mass function at high redshift. Monthly Notices of the Royal Astronomical Society. https://doi.org/10.1093/mnras/stae1547
