Low-oxygen galaxy recalls formation of the early universe

Astronomers say a small, simple galaxy like the newly discovered J0811+4730, can serve as an ideal proxy for the first generations of galaxies in the early universe. Photo by University of Virginia

Sept. 27 (UPI) — A newly discovered dwarf galaxy with a limited oxygen supply may offer astronomers new insights in the formation and evolution of the early universe.

The galaxy is 620 million light years away, situated in the constellation Lynx. Dubbed J0811+4730, the dwarf galaxy is the most oxygen-deprived star-forming galaxy yet discovered by astronomers. It boasts 9 percent less oxygen than the next most oxygen-deficient galaxy.

Because the first few generations of galaxies were relatively simple and oxygen-deprived, researchers believe J0811+4730 can offer unique insights into the history of the early universe.

The first generation of galaxies, which formed roughly 400 million years after the Big Bang, were relatively simple — made up of hydrogen and helium. Over time, the universe became more chemically diverse as stellar fusion birthed new, heavier elements, including oxygen.

The earliest low-oxygen galaxies are too faint and faraway to be studied using today’s astronomical equipment, but J0811+4730 can serve as a proxy for the smaller, simpler galaxies of the early universe — a window into the universe as it was 13 billion years ago.

“We found that a considerable fraction of the stellar mass of the galaxy was formed only a few million years ago, making this one of the best counterparts we’ve found of primordial galaxies,” Trinh Thuan, an astronomer at the University of Virginia, said in a news release. “Because of its extremely low oxygen level, this galaxy serves as an accessible proxy for star-forming galaxies that came together within one to two billion years after the Big Bang, the early period of our nearly 14 billion-year-old universe.”

Researchers believe J0811+4730 can also help them better understand how star formation encouraged re-ionization of the early universe. As more stars were born and galaxies coalesced, neutral hydrogen lurking in interstellar space once again became ionized plasma.

The latest findings — detailed this week in the journal Monthly Notices of the Royal Astronomical Society — suggest J0811+4730 is quite young and producing plenty of new stars and significant amounts of ionizing radiation.


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