Protostars and Planets VI, Heidelberg, July 15-20, 2013
Assembling Kepler\'s tightly-packed planetary systems
Hands, Thomas (University of Leicester)
Alexander, Richard (University of Leicester)
The Kepler mission has recently discovered a number of exoplanetary systems, such as Kepler-11 and Kepler-32, in which ensembles of several planets are found in very closely packed orbits (often within a few percent of an AU of one another). These systems present a challenge for traditional formation and migration scenarios, since these planets presumably formed larger orbital radii, before migrating inwards. In particular, it is difficult to understand how planets in such systems could have migrated across strong mean-motion resonances without becoming trapped, and remaining relatively well-spaced. It is also difficult to explain how such systems remain dynamically cold, as resonant interactions tend to excite orbital eccentricity and lead to close encounters. We present a dynamical study of the evolution these systems using an N-body approach, incorporating both smooth and stochastic migration forces and a variety of initial conditions. We highlight planetary architectures which seem particularly difficult to build, and discuss the implications of our results for the formation and evolution of such systems.
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