Stars form in clusters from large clouds of gas and dust. The Milky Way forms star clusters with masses 10,000 times that of our Sun. A new study shows that other galaxies can easily form much bigger clusters, which can be millions of times the mass of our Sun. There’s a catch though: These galaxies must be merging.
As reported in a paper in the Monthly Notices of the Royal Astronomical Society, observations of six merging pairs of galaxies suggest that star clusters up to 1 million solar masses can form in these collisions. An increase in star formation for colliding galaxies was well established, but the estimate of how it is concentrated in large clusters is an important insight into galaxy evolution.