On the Formation of Eccentric Superplanets

Abstract

. Among several emerging classes of the extrasolar planets there is a puzzling class of three `planets' on highly eccentric orbits around: 70 Vir, HD114762, and 16 cyg B. At least the first two of them appear to have been born this way. They have significantly super-Jovian minimum masses close to 10 Jupiter masses, and can thus be called "superplanets". They may represent either planets or brown dwarfs. I briefly discuss some recent theories of the origin of such bodies, grouped in the following categories: (A) direct molecular cloud fragmentation, (B) protostellar disk fragmentation theories, (C) companion star-planet interaction (if the host star is double, like 16 Cyg AB), (D) classical giant planet formation followed by planet-planet interaction, and (E) resonant disk-planet interaction, predicting low orbital eccentricity for planets and high eccentricities for superplanets and stars. Theories (C)--(E) seem to best explain the bulk of observations to date. 1. The diversity of pla..