Stars may grow to great mass if they're born in a cradle of older stars that confine and feed gas to younger ones among them, Canadian astronomers say. Researchers led by astronomers at the University of Toronto say the finding explains why stars at least 10 times as massive as the sun -- which should not exist -- can, in fact, form. As stars grow they tend to push away the gas they're feeding on, starving their own growth. The new finding could explain how they overcome this hurdle, a university release reported Wednesday. The astronomers report they've seen signs of collective gas "feeding" -- technically, "convergent constructive feedback" -- in a giant cloud of gas and dust called Westerhout 6,500 light years from Earth. The densest region of the cloud was surrounded by a congregation of old high-mass stars, they said, suggesting a previous generations of large stars enabled the next ones to grow massive, and close to each other. Like young stars, older stars also radiate and push gas away, and if such older stars happen to be arranged favorably around a major reservoir of gas, they can compress it enough to ignite new stars, the astronomers said. "This observation may lift the veil on the formation of the most massive stars which remains, so far, poorly understood," said Alana Rivera-Ingraham at the Institut de Recherche en Astrophysique et Planetologie in Toulouse, France, who led the study while she was a graduate student at Toronto.