Free Astronomy Magazine November-December 2024

38 NOVEMBER-DECEMBER 2024 Potential missing link to first stars in odd galaxy by NASA/ESA/CSA Leah Ramsay Christine Pulliam T he galaxy GS-NDG-9422 may easily have gone unnoticed. However, what appears as a faint blur in this James Webb Space Tele- scope NIRCam (Near-Infrared Cam- era) image may actually be a groundbreaking discovery that points astronomers on a new path of understanding galaxy evolution in the early universe. [NASA, ESA, CSA, STScI, Alex Cameron (Oxford)] models of cosmic gas clouds heated by very hot, massive stars, to an ex- tent that the gas shone brighter than the stars, was nearly a perfect match to Webb’s observations. “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,” said Katz. 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 de- grees Fahrenheit (80,000 degrees Celsius). The research team suspects that the galaxy is in the midst of a brief phase of intense star formation in- side a cloud of dense gas that is pro- ducing a large number of massive, hot stars. The gas cloud is being hit with so many photons of light from the stars that it is shining extremely brightly. In addition to its novelty, nebular gas outshining stars is in- triguing because it is something predicted in the environments of the universe’s first generation of stars, which astronomers classify as Population III stars. L ooking deep into the early uni- verse with NASA’s James Webb Space Telescope, astronomers have found something unprece- dented: a galaxy with an odd light signature, which they attribute to its gas outshining its stars. Found approximately one billion years af- ter the big bang, galaxy GS-NDG- 9422 (9422) may be a missing-link phase of galactic evolution between the universe’s first stars and familiar, well-established galaxies. “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 Uni- versity of Oxford. Cameron reached out to colleague Harley Katz, a theorist, to discuss the strange data. Working together, their team found that computer