By Ron Cowen
A group of young, hot stars in and near the constellation Scorpius shine brightly, making a memorable sight in the southern night sky. But if Narciso Benítez of Johns Hopkins University in Baltimore and his colleagues are correct, this collection of stars could have a lot to answer for. One of its members may have exploded in the solar systems neighborhood 2 million years ago, causing the widespread destruction of a variety of marine species here on Earth.
About 35 of the thousands of stars in this group, known as the Scorpius-Centaurus (Sco-Cen) OB association, weigh several times as much as the sun. These heavyweights–the groups brightest stars–tend to end their relatively brief lives with a powerful bang called a supernova. Other astronomers have determined that previous supernovas within the Sco-Cen association carved out the Local Bubble, a low-density cavity of interstellar gas that extends about 150 light-years around the sun (SN: 4/20/96, p. 248).