On July 10, 2012,The Astrophysical Journal published a paper which reveals a formation scenario for a special planetary configuration observed by Kepler Mission for the first time. This work was carried out by the research group of planetary sciences and deep space exploration.

 

The KeplerMission, launched in 2009 March, photometrically monitors a large patch of sky with sufficient precision to detect terrestrial-sized planets in potentially habitable orbits. The detailed statistical analysis of the data release over 16 months suggests that the fraction of multiple planetary systems is about 20%. Among these systems, KOI-152 is a special one with three planets trapped in near 1:2:4 mean motion resonances.

 

They proposed a scenario to produce a configuration of KOI-152. It is unlikely that planets in the system formed in situ; the planets probably underwent orbital migration during the formation and evolution process. First, three planets are assumed to have formed in the region away from the star with their nominal masses. Then, the planets may undergo type I or II migration due to interaction with the gaseous disk until they halt at the inner region of the disk. In this phase, three planets are trapped into mean motion resonances during the migration. Finally, tidal effects, arising from the central star, circularize their orbits.

 

The new formation scenario may be suitable to account for the formation of other systems with planetary configurations like KOI-152. http://iopscience.iop.org/0004-637X/753/2/170/