Astronomers have a good idea of how small stars such as our sun form. First, a spinning gas cloud collapses to become a dense core surrounded by a flattened disk of gas and dust. Matter from the disk then falls onto the central body, which becomes massive and dense enough to ignite nuclear reactions. As most of this material careens inward, some of it also spews outward in a pair of jets.
For rarer, heavier stars, the process isn't as clear. Some scientists have argued that as stars get bigger, they emit intense radiation whose pressure breaks up the surrounding disk, limiting the star's final size. These astronomers suggest instead that massive stars might arise from the merger of several sm