Hefty Find: Density has starring role in making stars massive

From their earliest moments, massive stars play the heavy. As infants, their fierce winds and harsh ultraviolet radiation tear away at the fragile gas clouds in which their lighter-weight cousins are born. Eventually, these behemoths explode, dumping vast amounts of energy into space along with an assortment of heavy elements.

Yet for all the drama, astronomers aren't quite sure how these rare, oversized stars form. Gas clouds—the material out of which all stars coalesce—typically divide into fragments much too small to make stars 10 to 100 times as massive as the sun.

In the Feb. 28 Nature, two