Researchers at University College London and the University of Potsdam have discovered two massive touching stars in a neighbouring galaxy that are on course to become black holes. The stars, located in the Small Magellanic Cloud, are in partial contact and swapping material with each other, with one star currently “feeding” off the other. They orbit each other every three days and are the most massive touching stars yet observed. The researchers found that, in the best-fit model, the star that is currently being fed on will become a black hole and will feed on its companion star. The surviving star will become a black hole shortly after. These black holes will form in only a couple of million years, but will then orbit each other for billions of years before colliding with such force that they will generate gravitational waves – ripples in the fabric of space-time – that could theoretically be detected with instruments on Earth.
