Free Astronomy Magazine September-October 2024

18 SEPTEMBER-OCTOBER 2024 ASTRO PUBLISHING in the cosmos. Webb’s instruments are so sensitive that they were able to detect an unusual amount of dense gas surrounding these galaxies. This gas will likely end up fueling the for- mation of new stars in the galaxies. “These galaxies are like sparkling islands in a sea of otherwise neu- tral, opaque gas,” explained Kasper Heintz, the lead author and an as- sistant professor of astrophysics at the Cosmic Dawn Center (DAWN) at the University of Copenhagen in Denmark. “Without Webb, we would not be able to observe these very early galaxies, let alone learn so much about their formation.” “We’re moving away from a picture of galaxies as isolated ecosystems. At this stage in the history of the universe, galaxies are all intimately connected to the intergalactic medium with its filaments and structures of pristine gas,” added Simone Nielsen, a co-author and PhD student also based at DAWN. In Webb’s images, the galaxies look like faint red smudges, which is why extra data, known as spectra, were critical for the team’s conclusions. Three galaxies actively forming only 400 to 600 million years after the Big Bang by NASA/ESA/CSA Claire Blome Christine Pulliam R esearchers analyzing data from NASA’s James Webb Space Tele- scope have pinpointed three galaxies that may be actively forming when the universe was only 400 to 600 million years old. Webb’s data show these galaxies are surrounded by gas that the researchers suspect to be almost purely hydrogen and helium, the earliest elements to exist