Alex Cameron of the University of Oxford, UK, who led the research, shared his initial reaction to the data: "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."
Collaborating with theorist Harley Katz, the team determined that the light signature from GS-NDG-9422 closely matches theoretical models of gas clouds illuminated by massive, extremely hot 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," explained Katz, who is affiliated with both Oxford University and the University of Chicago, USA.
Stars in this galaxy are estimated to have temperatures exceeding 80,000 degrees Celsius, significantly hotter than typical stars in today's Universe, which range between 40,000 and 50,000 degrees Celsius. The team suggests that the galaxy is in the midst of an intense star formation phase within a dense gas cloud. The cloud is being bombarded with photons from the stars, causing it to shine exceptionally bright - outshining even the stars themselves.
This phenomenon, where nebular gas outshines stars, is of particular interest because it mirrors conditions theorized to have existed in the Universe's first generation of stars, known as Population III stars. However, Cameron's team concluded that GS-NDG-9422 does not contain these primordial stars, as the Webb data showed more chemical complexity than would be expected from such stars. Harley Katz elaborated, "Its stars are different from 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."
While GS-NDG-9422 is currently the only example of this stage in galactic evolution, the researchers are eager to explore whether these conditions were common during that period or rare. They are actively searching for more galaxies from this era to broaden their understanding of the Universe's first billion years.
"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 remarked. "We are just at the beginning of new discoveries and understanding."
Research Report:Nebular dominated galaxies: insights into the stellar initial mass function at high redshift
Related Links
Webb at ESA
Understanding Time and Space
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