A shroud of gas swaddling a massive star has been seen to glow from its own heat for the first time, reveal astronomers. The discovery backs a theory that the heavy giants form from a clouds of gas collapsing into rotating disks.Understanding the origins of the massive stars - those with about ten to a hundred times more mass than the Sun - is important as they may provide insight on the early universe.Observations from the UK Infrared Telescope in Hawaii show that the gas cocoon around a massive star 20,000 light years away from Earth glows from violent shock waves.Gas and dust disks - thought to be the birthplace of planets - have been seen circling about 50 young Sun-like stars. But the disks have appeared only as dark silhouettes against brighter background gas or as longer wavelength radio emission from extremely cold disks.

Only a handful of gas disks have been detected around massive stars. The study, led by Nanda Kumar at the University of Porto in Portugal, is the first to capture high-resolution infrared images which give clues to the disk's own glow and dynamics.

"I think it is a very interesting piece of work because it addresses a fundamental question in massive-star formation theory," says Jonathan Tan, an astrophysicist at Princeton University in the US. "Do these stars form via an accretion disk, as low-mass, Sun-like stars do? Or is there a completely different mechanism?"


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