Science & Tech

Planetary survivor strategy: Outeat, outweigh, outlast!

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Growing planets must fight for survival against their suns

Astronomers Myron Lecar and Dimitar Sasselov have found that planet formation is a contest, where a growing planet must fight for survival lest it be swallowed by the star that initially nurtured it. Of the first 100 stars found to harbor planets, more than 30 stars host a Jupiter-sized world in an orbit smaller than Mercury’s, whizzing around its star in a matter of days (as opposed to our solar system where Jupiter takes 12 years to orbit the Sun). Such close orbits result from a race between a nascent gas giant and a newborn star. This research is described in the Oct. 10, 2003 issue of The Astrophysical Journal Letters. “The endgame is a race between the star and its giant planet,” says Sasselov. “In some systems, the planet wins and survives, but in other systems, the planet loses the race and is eaten by the star.”