Kepler1656b: A Dense SubSaturn with an Extreme Eccentricity
Abstract
Kepler1656b is a 5 {R}_{\oplus } planet with an orbital period of 32 days initially detected by the prime Kepler mission. We obtained precision radial velocities of Kepler1656 with Keck/HIRES in order to confirm the planet and to characterize its mass and orbital eccentricity. With a mass of 48 ± 4 {M}_{\oplus }, Kepler1656b is more massive than most planets of comparable size. Its high mass implies that a significant fraction, roughly 80%, of the planet’s total mass is in highdensity material such as rock/iron, with the remaining mass in a lowdensity H/He envelope. The planet also has a high eccentricity of 0.84 ± 0.01, the largest measured eccentricity for any planet less than 100 {M}_{\oplus }. The planet’s high density and high eccentricity may be the result of one or more scattering and merger events during or after the dispersal of the protoplanetary disk.
 Publication:

The Astronomical Journal
 Pub Date:
 October 2018
 DOI:
 10.3847/15383881/aad773
 arXiv:
 arXiv:1809.08436
 Bibcode:
 2018AJ....156..147B
 Keywords:

 planets and satellites: detection;
 planets and satellites: dynamical evolution and stability;
 planets and satellites: formation;
 planets and satellites: individual: Kepler1656;
 techniques: photometric;
 techniques: radial velocities;
 Astrophysics  Earth and Planetary Astrophysics
 EPrint:
 10 pages, 6 figures, published in The Astronomical Journal