Astronomers using the James Webb Space Telescope have spotted a weird galaxy that originated just a billion years after the Big Bang. Its strange properties are helping researchers to piece together how early galaxies formed, and to inch closer to one of astronomy’s holy grail discoveries: the very earliest stars.
The researchers used Webb’s instruments to look at the light coming from the GS-NDG-9422 galaxy across different wavelengths, called a spectrum, and made some puzzling findings.
“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,” said lead researcher Alex Cameron of the University of Oxford in a statement.
The light coming from this galaxy suggested that its gas was actually shining more brightly than its stars, which must be caused by the stars being extremely hot and warming up the gas. While large, hot stars typically have temperatures of 40,000 to 50,000 degrees Celsius, the stars seen in this galaxy were calculated to be over 80,000 degrees Celsius.
This is already an interesting finding, but what makes it particularly special is that it could help uncover some of the earliest stars thought to exist, called Population III stars. Star populations are numbered backwards, so the stars we see born today are Population I, and older stars are Population II. Scientists have long predicted the existence of an even older group of stars called Population III, which were those that existed in the earliest stages of the universe, but they have not yet found direct evidence of them.
These Population III stars would have almost no heavy elements in them, because these heavier elements had not yet been created by supernovae. So they would be quite different from the stars that we see today.
“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 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,” said fellow researcher Harley Katz.
The researchers are now looking for more of these weird galaxies to learn more about how stars were forming in the first 1 billion years after the Big Bang.
“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.”
The research is published in the journal Monthly Notices of the Royal Astronomical Society.