The most popular view has been that such supermassive stars form when two large stars collide, but new observations cast doubt on that model.
Centrifuge
IRAS 04368+2557 is a protostar about 450 light years from us. It is a particularly young protostar, at about 300,000 years. Because of its age and proximity, it provides an excellent opportunity to study the early stages of stellar and planetary formation.
When Worlds Collide
The discovery of protoplanetary disks such as this one agree with the nebular hypothesis, which posits that a star and planetary system form together. The star collapses out of a nebula, and it forms an accretion disk around itself, out of which the planets form.