Many worlds discovered by Kepler survived ruthless culling
Sibling rivalries among planets can turn deadly. Families of worlds huddled close to their stars might destroy one another, leaving behind just one or two planets after the carnage. These family feuds probably erupt in planetary systems that form much differently than our own, though it’s possible our solar system suffered similar growing pains.
Many multiplanet systems discovered by the Kepler space telescope live on the edge of stability, astrophysicist Yanqin Wu and her student Bonan Pu report online February 19 at arXiv.org. If the planets were any closer together, they would have already nudged each other off course and collided. Pu and Wu, both of the University of Toronto, propose that the planets in these systems are survivors from a more diverse population. Over time, planets that formed even closer together were whittled away until just one or two worlds remained.