Astronomers using ALMA have discovered galaxy Y1, a 'star factory' forming roughly 180 stars per year — about 180 times the Milky Way's rate. The galaxy's light took more than 13 billion years to arrive, showing Y1 as it was ~600 million years after the Big Bang, and measurements of superheated dust confirm its ultraluminous nature. Objects like Y1 could explain how some galaxies grew so rapidly in the early universe; the team plans further ALMA observations to find and study more such systems.
ALMA discovers a 'star factory' forming 180 stars a year — a clue to rapid galaxy growth after the Big Bang
Astronomers using ALMA have discovered galaxy Y1, a 'star factory' forming roughly 180 stars per year — about 180 times the Milky Way's rate. The galaxy's light took more than 13 billion years to arrive, showing Y1 as it was ~600 million years after the Big Bang, and measurements of superheated dust confirm its ultraluminous nature. Objects like Y1 could explain how some galaxies grew so rapidly in the early universe; the team plans further ALMA observations to find and study more such systems.
12:38 AM, 11/19/2025Science
ALMA discovers a superheated 'star factory' from the early universe
Astronomers using the Atacama Large Millimeter/submillimeter Array (ALMA) have identified a primordial galaxy, Y1, that was producing stars at an extraordinary rate — about 180 new stars per year, roughly 180 times the current rate of the Milky Way. The galaxy's light has taken more than 13 billion years to reach Earth, so we see Y1 as it was roughly 600 million years after the Big Bang.
Earlier observations detected glowing cosmic dust in Y1, marking the most distant direct detection of such dust to date. By measuring the temperature of that dust, the team confirmed Y1 is ultraluminous and superheated — an 'extreme' star-forming system that could help explain how some galaxies accumulated mass so rapidly in the universe's first billion years.
'We are looking back to an era when the universe was producing stars far more quickly than it does today,' said Tom Bakx, a postdoctoral researcher at Chalmers University of Technology who led the study. 'Measuring the dust temperature allowed us to confirm that Y1 hosts a different, superheated kind of star factory.'
Co-author Yoichi Tamura of Nagoya University added that while Y1 is the first galaxy of this kind observed, similar objects may have been common in the early universe. The research team plans to use ALMA's high-resolution capabilities to search for more examples and to study Y1's structure and star-forming processes in greater detail.
The discovery is reported in Monthly Notices of the Royal Astronomical Society in a paper titled 'A warm ultraluminous infrared galaxy just 600 million years after the Big Bang'.