Kepler-432: a red giant interacting with one of its two long-period giant planets

Quinn, Samuel N. and White, Timothy R. and Latham, David W. and Chaplin, William J. and Handberg, Rasmus and Huber, Daniel and Kipping, David M. and Payne, Matthew J. and Jiang, Chen and Aguirre, Victor Silva and Stello, Dennis and Sliski, David H. and Ciardi, David R. and Buchhave, Lars A. and Bedding, Timothy R. and Davies, Guy R. and Hekker, Saskia and Kjeldsen, Hans and Kuszlewicz, James S. and Everett, Mark E. and Howell, Steve B. and Basu, Sarbani and Campante, Tiago L. and Christensen-Dalsgaard, Jorgen and Elsworth, Yvonne P. and Karoff, Christoffer and Kawaler, Steven D. and Lund, Mikkel N. and Lundkvist, Mia and Esquerdo, Gilbert A. and Calkins, Michael L. and Berlind, Perry (2015) Kepler-432: a red giant interacting with one of its two long-period giant planets. The Astrophysical Journal, 803 (2). pp. 49-69. ISSN 0004-637X

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We report the discovery of Kepler-432b, a giant planet (Mb=5.41+0.036-0.039MJup,Rb=1.145+0.039-0.039RJup) transiting an evolved star (M∗=1.320.10-0.07M⊙, R∗=4.060.12-0.08R⊙,) with an orbital period of Pb=52.501129+0.000067-0.000053 days. Radial velocities (RVs) reveal that Kepler-432b orbits its parent star with an eccentricity of e=0.51340.0098-0.0089, which we also measure independently with asterodensity profiling (AP; e=0.5070.039-0.114), thereby confirming the validity of AP on this particular evolved star. The well-determined planetary properties and unusually large mass also make this planet an important benchmark for theoretical models of super-Jupiter formation. Long-term RV monitoring detected the presence of a non-transiting outer planet (Kepler-432c; Mcsin ic=2.43+0.22-0.24, days), and adaptive optics imaging revealed a nearby (), faint companion (Kepler-432B) that is a physically bound M dwarf. The host star exhibits high signal-to-noise ratio asteroseismic oscillations, which enable precise measurements of the stellar mass, radius, and age. Analysis of the rotational splitting of the oscillation modes additionally reveals the stellar spin axis to be nearly edge-on, which suggests that the stellar spin is likely well aligned with the orbit of the transiting planet. Despite its long period, the obliquity of the 52.5 day orbit may have been shaped by star-planet interaction in a manner similar to hot Jupiter systems, and we present observational and theoretical evidence to support this scenario. Finally, as a short-period outlier among giant planets orbiting giant stars, study of Kepler-432b may help explain the distribution of massive planets orbiting giant stars interior to 1 AU.

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Item Type: Article (Commonwealth Reporting Category C)
Refereed: Yes
Item Status: Live Archive
Additional Information: Access to published version in accordance with the copyright policy of the publisher.
Faculty/School / Institute/Centre: No Faculty
Faculty/School / Institute/Centre: No Faculty
Date Deposited: 02 Jun 2017 07:01
Last Modified: 27 Jun 2017 00:28
Uncontrolled Keywords: asteroseismology; planet; planets and satellites: dynamical evolution and stability; planets and satellites: Formation; planets and satellites: gaseous planets; star interactions; stars: individual (Kepler-432);
Fields of Research (2008): 02 Physical Sciences > 0201 Astronomical and Space Sciences > 020110 Stellar Astronomy and Planetary Systems
Socio-Economic Objectives (2008): E Expanding Knowledge > 97 Expanding Knowledge > 970102 Expanding Knowledge in the Physical Sciences
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