Economics 119, 001 - Fall 2013 Creative Commons 3.0: Attribution-NonCommercial-NoDerivs

For the full story, visit: http://news.berkeley.edu/2016/05/11/star-has-four-mini-neptunes-orbiting-in-lock-step/ A four-planet system observed several years ago by the Kepler spacecraft is actually a rarity: Its planets, all miniature Neptunes nestled close to the star, are orbiting in a unique resonance that has been locked in for billions of years. For every three orbits of the outermost planet, the second orbits four times, the third six times and the innermost eight times. Such orbital resonances are not uncommon – our own dwarf planet Pluto orbits the sun twice during the same period that Neptune completes three orbits – but a four-planet resonance is. Astronomers from the University of Chicago and University of California, Berkeley, who are reporting the discovery online May 11 in Nature, are particularly interested in this stellar system because our system’s four giant planets – Jupiter, Saturn, Neptune and Uranus – are thought to have once been in resonant orbits that were disrupted sometime during their 4.5-billion-year history. According to co-author Howard Isaacson, a UC Berkeley research astronomer, the Kepler-223 star system can help us understand how our solar system and other stellar systems discovered in the past few decades formed. In particular, it could help resolve the question of whether planets stay in the same place they formed, or whether they move closer to or farther from their star over the eons. ...