KEPLER-63b: A GIANT PLANET IN A POLAR ORBIT AROUND A YOUNG SUN-LIKE STAR

• Main Authors: Marcy, Geoffrey W. (Author), Howard, Andrew W. (Author), Isaacson, Howard (Author), Johnson, John Asher (Author), Torres, Guillermo (Author), Albrecht, Simon H. (Contributor), Campante, T. L. (Author), Chaplin, William J. (Author), Davies, Guy R. (Author), Lund, Mikkel N. (Author), Carter, Joshua Adam (Author), Dawson, Rebekah I. (Author), Buchhave, Lars A. (Author), Everett, Mark E. (Author), Fischer, Debra A. (Author), Geary, John C. (Author), Gilliland, Ronald L. (Author), Horch, Elliott P. (Author), Howell, Steve B. (Author), Latham, David W. (Author), Sanchis Ojeda, Roberto (Contributor), Winn, Joshua Nathan (Contributor)
• Other Authors: Massachusetts Institute of Technology. Department of Physics (Contributor), MIT Kavli Institute for Astrophysics and Space Research (Contributor)
• Format: Article
• Language: English
• Published: IOP Publishing, 2014-08-11T18:42:12Z.
• Subjects: Article
• Online Access: Get fulltext

 We present the discovery and characterization of a giant planet orbiting the young Sun-like star Kepler-63 (KOI-63, m [subscript Kp] = 11.6, T [subscript eff] = 5576 K, M [star] = 0.98 M [subscript ☉]). The planet transits every 9.43 days, with apparent depth variations and brightening anomalies caused by large starspots. The planet's radius is 6.1 ± 0.2 R [subscript ⊕], based on the transit light curve and the estimated stellar parameters. The planet's mass could not be measured with the existing radial-velocity data, due to the high level of stellar activity, but if we assume a circular orbit, then we can place a rough upper bound of 120 M [subscript ⊕] (3σ). The host star has a high obliquity (ψ = 104°), based on the Rossiter-McLaughlin effect and an analysis of starspot-crossing events. This result is valuable because almost all previous obliquity measurements are for stars with more massive planets and shorter-period orbits. In addition, the polar orbit of the planet combined with an analysis of spot-crossing events reveals a large and persistent polar starspot. Such spots have previously been inferred using Doppler tomography, and predicted in simulations of magnetic activity of young Sun-like stars.