Pollution alert in the early universe Read time: 3 minutes We all know about environmental pollution. The air is polluted by cars, airplanes and factories. Theoceans are polluted with plastic. Humans produce a lot of filth that spreads throughout our world,slowly but surely.Now, astronomers have discovered the first environmental pollution in the universe. It’s notproduced by humans, but by stars. But just like human filth, it is spreading away from its source.The very first stars in the universe were born from huge clouds of gas. Right after the big bang, theonly gases available were hydrogen and helium – other elements did not yet exist. But in the hotinteriors of stars, atoms of hydrogen and helium fused together into heavier elements, like carbonand oxygen. When stars grow old, they can blow some of these newly formed elements into space,just like a factory releases dirt into the atmosphere.Little surprise, then, that distant galaxies contain carbon atoms, floating around in the spacebetween the stars. But now, ALMA has revealed that this ‘cosmic pollution’ extends well beyond thegalaxies’ edge. It’s as if the pollution of factories in the United States turns out to extend all the wayacross the Atlantic and Pacific Oceans.By studying existing ALMA observations of remote galaxies, the astronomers discovered that thesegalaxies are surrounded by huge clouds of carbon gas. Apparently, the ‘pollution’ from stars in thegalaxy is somehow blown out into space. How? Perhaps by supernova explosions, or maybe bysupermassive black holes in the galaxy’s core. But no one knows for sure.The light from distant galaxies take billions of years to reach our telescopes here on Earth. Therefore,we see these galaxies as they were long ago, just one billion years after the big bang or so. No onehad expected that ‘cosmic pollution’ would already be so severe back then. In fact, scientists have nosatisfying explanation for the huge carbon clouds. Hopefully, the discovery will help astronomers tobetter understand the very first stages of the evolution of galaxies.Incidentally, we shouldn’t worry too much about this massive environmental pollution in the earlyuniverse. After all, life is based on carbon chemistry. Without the large-scale release and distributionof carbon atoms in the universe, we wouldn’t be here! What? The discovery of huge carbon clouds surrounding remote galaxies was not the result of new ALMAobservations. Instead, the astronomers combined existing observations of 18 distant galaxies thatwere available in the ALMA archive. By adding many earlier measurements together, they achievedenough sensitivity to detect the submillimeter radiation of ionized carbon – carbon atoms that havelost two electrons. In most cases, they found that the galaxies are enveloped in huge clouds ofcarbon gas. The clouds extend to distances of some 30,000 light-years – about five times the size ofthe galaxies themselves. Who? The discovery was made by an international team of astronomers, led by Seiji Fujimoto of theUniversity of Tokyo in Japan. Seiji worked together with colleagues from Japan, the United Kingdom,Italy, Germany, and the United States. They published their results in a major professional astronomymagazine called The Astrophysical Journal. ALMA URL