Weird galaxy: Did Webb find the missing link to first stars?

• New Galaxy Discovery: The James Webb Space Telescope found a galaxy where gas shines brighter than its stars.
• Understanding how galaxies formed: The discovery may be a missing-link to the evolution between the universe’s first stars and galaxies.
• Ongoing Research: Scientists will continue to explore gas’ role in star formation in the early universe.

The Royal Astronomical Society originally published this news release on September 25, 2024. Edits by EarthSky.

Webb discovers weird galaxy in early universe

The James Webb Space Telescope (JWST) spotted an extreme class of galaxy in the early universe. Astronomers say the discovery of a weird galaxy in the early universe could help us understand how the cosmic story began.

GS-NDG-9422 (9422) formed approximately 1 billion years after the Big Bang. It stood out because it has an odd, never-before-seen light signature that indicated its gas is outshining its stars.

Researchers say this is a new phenomena and a significant discovery. What’s more, it could be the missing-link phase of galactic evolution between the universe’s first stars and familiar, well-established galaxies.

According to the lead researcher Alex Cameron of the University of 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.

Researchers found gas outshining stars

Cameron reached out to colleague Dr Harley Katz, a theorist, to discuss the strange data. Working together, their team found that their computer models were nearly a perfect match to Webb’s observations. Cosmic gas clouds were heated by very hot, massive stars, to an extent that the gas shone brighter than the stars.

Katz, of Oxford and the University of Chicago said:

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.

In the local universe, typical hot, massive stars have a temperature ranging between 70,000 to 90,000 degrees Fahrenheit (40,000 to 50,000 degrees Celsius). According to the team, galaxy 9422 has stars hotter than 140,000 degrees Fahrenheit (80,000 degrees Celsius).

The researchers suspect that the galaxy is in a brief phase of intense star formation inside a cloud of dense gas that is producing a large number of massive, hot stars. So many photons of light from the stars are hitting the gas cloud that it is shining extremely brightly.

Gas outshining stars was predicted

In addition to its novelty, nebular gas outshining stars is intriguing because it is something predicted in the environments of the universe’s first generation of stars, which astronomers classify as Population III. They are hypothetical massive stars formed in the early universe and thought to contain only hydrogen and helium.

Katz explained:

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.

At this point, galaxy 9422 is one example of this phase of galaxy development, so there are still many questions to answer. Are these conditions common in galaxies during this period, or a rare occurrence? What more can they tell us about even earlier phases of galaxy evolution?

Cameron, Katz and their research colleagues are now identifying more galaxies to add to this population. This will offer a better understanding of what was happening in the universe within the first billion years after the Big Bang.

Cameron concluded:

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. We are just at the beginning of new discoveries and understanding.

Bottom line: Researchers using the James Webb Space Telescope discovered a galaxy in the early universe whose gas outshines its stars. Researchers say this could be a clue to what was happening in the early universe.

Source: Nebular dominated galaxies: insights into the stellar initial mass function at high redshift

Via Royal Astronomical Society

Read more: Star clusters found in the Cosmic Gems arc by Webb