Astronomers detect water in one of the oldest known galaxies
Astronomers have detected traces of water in one of the oldest known galaxies, proving for the first time that the life-giving substance played a role in the formation of the earliest stars. The galaxy, called SPT0311-58, is located some 12.88 billion light years from Earth, meaning that our telescopes see it as it looked only 1 billion years after the
Big Bang. Astronomers estimate that the galaxy is only 780 million years old, an age at which stars formed at a much higher rate than they do in more mature galaxies.
The observation, the most distant detection of water in the universe, was made by the Atacama Large Millimeter/submillimeter Array (ALMA), a powerful radio telescope in northern Chile in the Atacama Desert. In addition to water, ALMA also detected carbon monoxide. SPT0311-58, discovered by ALMA in 2017, is the most massive currently known galaxy of this ancient age, and actually consists of two galaxies that appear to be merging. It has more gas and dust compared to galaxies at closer distances, which are more mature.
Astronomers currently don’t understand how such huge amounts of gas and dust assembled in the young universe to form the first stars and early galaxies. But they do know that stars in young galaxies form at a thousand times greater rate than in the Milky Way. Water is the third most common molecule in the universe after hydrogen and carbon monoxide, and some studies suggest that it might be used as a signature of star formation.