Growing pains aren’t just for awkward teens: Thanks to a chance alignment of galaxies, astronomers have detected a massive loss of gas from an ancient galaxy that’s dramatically slowing the rate of stars forming there, a finding that sheds light on star formation in the early universe.
The distant group of stars, known as SPT2319-55, is more than 12 billion light-years away from Earth—which means researchers are observing the galaxy as it was when the universe was only 1 billion years old. Objects that far away are typically too faint to observe in detail, but the gravitational effects of a massive galaxy between that star group and Earth bends SPT2319-55’s light like a lens, which both focuses the light and intensifies its features.
When astronomers looked at the wavelengths at which hydroxyl molecules in the galaxy absorbed light, they noted a big shift—which, in turn, reveals that immense clumps of gas and dust are being flung from the galaxy at speeds of up to 800 kilometers per second (artist’s representation, above). That outflow is propelled by pressure waves created by the explosions of large numbers of dying stars. Altogether, that material would be enough to create more than 500 stars the size of our sun each year, the researchers report online today in Science.
Because the estimated escape velocity from SPT2319-55 is about 650 kilometers per second, some of that gas and dust—about 10% of it, the researchers estimate—will be forever lost to intergalactic space. But the rest of it will eventually fall back into the galaxy, fueling new waves of star growth there for tens of millions of years.