Analysis of distant galaxies imaged by NASA’s James Webb Space Telescope shows that they are extremely young and bear a striking resemblance to a rare type of small galaxy known as the “green pea” that exists in our cosmic backyard.

“With detailed chemical fingerprints of these early galaxies, we can see that they formed perhaps the most primitive galaxy ever identified. James Rhodes, an astrophysicist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, said: We can connect it with galaxies and examine it in much more detail.” The results of the 241st meeting are the American Astronomical Society in Seattle.

The Pea Green Galaxies were discovered and named in 2009 by volunteers at the Galaxy Zoo, a project where citizen scientists help classify galaxies in images, starting with those in the Sloan Digital Sky Survey. The peas stood out as small, round, indistinct dots with a distinct green hue, a result of both the colors assigned to different filters in the composite survey images and the properties of the galaxies.

The colors of pea-green galaxies are unusual because most of their light comes from brightly glowing gas clouds. Gases emit light of a specific wavelength, unlike stars, which constantly produce an iridescent spectrum of colors. Peas are also quite compact, typically only about 5,000 light-years in diameter, or about 5% of our Milky Way galaxy.

“Peas may be small, but their star-forming activity is extremely intense for their size, so they emit bright ultraviolet light,” said Keuho Kim, a postdoctoral researcher at the University of Cincinnati and a member of the analysis team. “Ultraviolet images of the green pea taken by Hubble and ground-based studies of early star-forming galaxies make it clear that both have this feature.”

In July 2022, NASA and Webb mission partners released the deepest and clearest infrared image ever seen of the distant universe, capturing thousands of galaxies in and behind a cluster known as SMACS 0723. The mass of the cluster makes it a gravitational lens, both magnifying and magnifying. and distorts the view of background galaxies. Among the faintest galaxies behind the cluster were three compact infrared objects that looked like they might be distant relatives of the green pea. The farthest of these three galaxies was magnified about 10 times and provided significant help from nature in addition to the telescope’s unprecedented capabilities.

Webb did more than just view the cluster; The Near Infrared Spectrograph (NIRSpec) instrument also captured the spectrum of selected galaxies in the scene. When Rhodes and his colleagues analyzed these measurements and corrected for wavelength emitted by the expansion of space, they found that the signature features emitted by oxygen, hydrogen, and neon lined up with striking resemblance to those seen from a nearby green pea.

In addition, Webb spectra made it possible for the first time to measure the amount of oxygen in these cosmic dawn galaxies.

As stars produce energy, they convert lighter elements such as hydrogen and helium into heavier elements. When stars explode or lose their outer layers at the end of their lifetimes, these heavy elements mix with the gas that makes up the next generation of stars, and the process continues. Throughout cosmic history, stars have continually enriched the universe.

Two of the Webb galaxies contain oxygen at about 20% of the level of our Milky Way. After all, they look like a typical green pea, making up less than 0.1% of the nearby galaxies seen in Sloan’s study. The third galaxy studied is even more unusual.

“We see these objects as they existed until 13.1 billion years ago, when the age of the universe was about 5% of its current age,” said Goddard researcher Sangeeta Malhotra. “And we see that these are young galaxies in every sense – filled with young stars and glowing gas containing a few recycled chemical products from earlier stars. Indeed, a galaxy like ours contains only 2% of the oxygen and may be the most primitive galaxy ever chemically identified. “