"The first thing I thought when I saw the galaxy's spectrum was, 'that's strange,'" said Alex Cameron, lead researcher from the University of Oxford. "That's exactly what Webb was designed for-revealing new phenomena in the early universe that help us understand how everything began."
Cameron consulted with Harley Katz, a theorist from Oxford and the University of Chicago. Together, their team found that the data from the galaxy matched predictions made by computer models of cosmic gas clouds heated by massive, extremely hot stars. These stars appear to heat the gas to the point where it outshines the stars themselves.
"These stars seem to be much hotter and more massive than those in the local universe, which makes sense given that the early universe was a much different environment," said Katz.
In comparison, hot, massive stars in our local universe reach temperatures between 70,000 to 90,000 degrees Fahrenheit (40,000 to 50,000 degrees Celsius). In contrast, the stars in galaxy 9422 exceed 140,000 degrees Fahrenheit (80,000 degrees Celsius).
Researchers believe the galaxy is undergoing a brief phase of intense star formation within a dense gas cloud, which is generating a large number of these exceptionally hot stars. The gas cloud is bombarded by photons from these stars, causing it to glow intensely.
What makes this discovery particularly fascinating is that this type of nebular gas outshining the stars has been predicted for environments associated with the first stars in the universe, known as Population III stars.
"We know this galaxy doesn't contain Population III stars because Webb's data reveals too much chemical complexity," Katz explained. "However, the stars here are unlike those we know, and they may help us understand how galaxies transitioned from primordial stars to more familiar types."
As of now, GS-NDG-9422 is the only known example of this galactic phase, leaving many unanswered questions. Researchers are actively seeking more examples to determine whether these conditions were common or rare during this period, as well as what they can reveal about even earlier stages of galactic evolution.
"It's an exciting time to be using the Webb telescope to explore this previously inaccessible time in the universe," Cameron said. "We're just beginning to uncover new discoveries and insights."
Research Report:Nebular dominated galaxies: insights into the stellar initial mass function at high redshift
Related Links
Webb Space Telescope
Stellar Chemistry, The Universe And All Within It
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