Free Astronomy Magazine January-February 2026

29 JANUARY-FEBRUARY 2026 ASTRO PUBLISHING “We’re looking back to a time when the universe was making stars much faster than today. Previous observa- tions revealed the presence of dust in this galaxy, making it the furthest away we've ever directly detected light from glowing dust. That made us suspect that this galaxy might be running a different, superheated kind of star factory. To be sure, we set out to measure its tempera- ture,” says Tom Bakx. Stars like our Sun are forged in huge, dense clouds of gas in space. The Orion Nebula and the Carina Nebula are two examples of such star factories. They shine brightly in the night sky, powered by their youngest and most massive stars, which light up clouds of gas and dust in many dif- ferent colours. At wavelengths longer than the human eye can see, star factories shine brightly thanks to huge num- bers of tiny grains of cosmic dust, heated by starlight. To be able to probe the galaxy's temperature, the scientists needed the superior sensi- tivity of ALMA. One of the world's largest telescopes, ALMA’s dry, high- altitude location in Chile made it possible to image the galaxy in just the right colour, at a wavelength of 0.44 millimetres using its Band 9 in- strument. “At wavelengths like this, the galaxy is lit up by billowing clouds of glowing dust grains. When we saw how bright this galaxy shines compared to other wave- lengths, we immediately knew we were looking at something truly special,” says Tom Bakx. The detec- tion showed the galaxy’s dust glow- ing at a temperature of 90 Kelvin – around -180 degrees Celsius. “The temperature is certainly chilly com- pared to household dust on Earth, but it’s much warmer than any other comparable galaxy we’ve seen. This confirmed that it really is an ex- treme star factory. Even though it’s the first time we’ve seen a galaxy like this, we think that there could be many more out there. Star facto- ries like Y1 could have been com- mon in the early universe,” says team member Yoichi Tamura, as- tronomer at Nagoya University, Japan. Y1 is manufacturing stars at the extreme rate of over 180 solar masses per year, an unsustainable pace that cannot last long. On average, our galaxy, the Milky Way, creates only about one solar mass per year. Brief, hidden bursts of star formation, as seen in Y1, may have been common in the early universe, the scientists suspect. “We don't know how common such phases might be in the early uni- verse, so in the future we want to look for more examples of star fac- tories like this. We also plan to use the high-resolution capabilities of ALMA to take a closer look at how this galaxy works,” says Tom Bakx. Bakx’s team believes that galaxy Y1 may help solve another cosmic mys- tery. Earlier studies have shown that galaxies in the early universe ap- pear to have far more dust than their stars could have produced in the short time they have been shining. Astronomers have been puzzled by this, but Y1’s unusual temperature points to a solution. Team member Laura Sommovigo, astrophysicist at the Flatiron Insti- tute and Columbia University, USA, takes up the story. “Galaxies in the early universe seem be too young for the amount of dust they con- tain. That’s strange, because they don’t have enough old stars, around which most dust grains are created. But a small amount of warm dust can be just as bright as large amounts of cool dust, and that’s exactly what we’re seeing in Y1. Even though these galaxies are still young and don’t yet contain much heavy elements or dust, what they do have is both hot and bright,” she concludes. G lowing deep red from the distant past: galaxy Y1 shines thanks to dust grains heated by newly-formed stars (circled in this image from the James Webb telescope). [NASA, ESA, CSA, STScI, J. Diego (Instituto de Física de Cantabria, Spain), J. D’Silva (U. Western Australia), A. Koekemoer (STScI), J. Summers & R. Windhorst (ASU), and H. Yan (U. Missouri)] grown quickly when the universe was very young, solving a long- standing puzzle for astronomers. The first generations of stars formed under conditions very dif- ferent from anywhere we can see in the nearby universe today. As- tronomers are studying these differ- ences using powerful telescopes that can detect galaxies so far away their light has travelled towards us for billions of year. Now, an interna- tional team of astronomers led by Tom Bakx at Chalmers University of Technology in Sweden has meas- ured the temperature of one of the most distant known star factories. The galaxy, known as Y1, is so far away that its light has taken over 13 billion years to reach us. !