Astronomers have found a distant galaxy that’s building stars 180 times faster than our own Milky Way—offering a new clue to how galaxies grew so rapidly in the early universe.
The galaxy, known as MACS0416_Y1 or simply Y1, lies so far away that its light has taken more than 13 billion years to reach us.
That means astronomers are seeing it as it appeared when the universe was still very young.
Y1 is located behind a cluster of galaxies called MACS0416, about 4 billion light years away in the constellation Eridanus, also known as the River.
An international team of researchers led by Dr. Tom Bakx from the Chalmers University of Technology in Sweden studied Y1 using the Atacama Large Millimeter/submillimeter Array (ALMA) telescope in Chile.
ALMA can detect faint signals from distant galaxies that are invisible to normal telescopes.
By measuring the heat of the dust inside Y1, the team discovered that this galaxy is a “superheated star factory.”
“We’re looking back to a time when the universe was making stars much faster than today,” said Bakx. “We already knew Y1 had dust, but its brightness told us it might be forming stars in a completely different way.”
Stars form inside massive clouds of gas and dust, like those found in the Orion and Carina Nebulae in our own galaxy.
When newborn stars shine, they heat up the surrounding dust, making it glow at wavelengths invisible to the human eye.
ALMA’s sensitive instruments allowed the scientists to detect this glow in Y1 at a wavelength of 0.44 millimeters—revealing that the dust is unusually hot.
The galaxy’s dust temperature was measured at 90 Kelvin, or about –180°C. Although that sounds cold, it’s significantly warmer than the dust found in other galaxies of similar age.
“This confirmed that Y1 is an extreme star-forming galaxy,” said co-researcher Dr. Yoichi Tamura from Nagoya University in Japan. “Even though this is the first time we’ve seen a galaxy like this, there could be many more out there.”
Y1 is producing new stars at a breathtaking rate of more than 180 solar masses per year, compared to just one solar mass per year in the Milky Way. This rapid pace cannot last long, but researchers believe short, intense bursts of star formation like this may have been common in the early universe.
The discovery also helps explain a long-standing mystery: why ancient galaxies seem to contain more dust than expected. According to Dr. Laura Sommovigo from the Flatiron Institute and Columbia University, “A small amount of warm dust can shine as brightly as a large amount of cold dust. That’s exactly what we see in Y1.”
These new findings suggest that galaxies in the early universe didn’t need huge amounts of dust to shine brightly—they just needed it to be hot.
