Moon and Antares
Antares, the leading light of a five-million-year-old family, huddles close to the Moon tonight. The brightest star of Scorpius is a little below the Moon. Many of its siblings stand to its upper right, including the three stars that outline the scorpion's flat head.
The stars are members of the Upper Scorpius Association -- a group of about 2500 star systems that all formed from a single giant cloud of gas and dust.
Their birth most likely was triggered by the death of a massive star about 12 million years ago. The shock wave from the explosion compressed a nearby cloud of gas and dust. The material broke up into small clumps that condensed to form new stars. The stars ranged from a fraction of the mass of the Sun to many times its mass.
The heaviest stars included Antares. They produced intense radiation and strong winds that blew away most of the remaining gas and dust, ending the process of star birth.
Antares was probably the second-heaviest of the bunch. The heaviest, which was perhaps 50 times as massive as the Sun, exploded as a supernova about a million-and-a-half years ago. Its shockwave cleared out any wisps of gas and dust that were left around. And as it swept outward, it ran into another giant cloud, triggering a new round of star birth there.
Sometime in the next million years or so, Antares is likely to explode as a supernova as well -- perhaps helping to create another new family of stars.
Script by Damond Benningfield, Copyright 2011
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