HAT-P31bc:A Transiting, Eccentric, Hot Jupiter and a Long-Period, Massive Third Body

• Published in: The Astronomical Journal
• Main Authors: Kipping, D. M., Hartman, J., Bakos, G. Ã., Torres, G., Latham, D. W., Bayliss, D., Kiss, L. L., Sato, B., Béky, B., Kovács, Géza, Quinn, S. N., Buchhave, L. A., Andersen, J., Marcy, G. W., Howard, A. W., Fischer, D. A., Johnson, J. A., Noyes, R. W., Sasselov, D. D., Stefanik, R. P., Lázár, J., Papp, I., Sári, P., Fűrész, G.
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: American Astronomical Society 2011
• Subjects: planetary systems; stars: individual (HAT-P-31; GSC 2099-00908); techniques: photometric; techniques: spectroscopic; Jupiter; Norway; Observatorio; Iceland
• Online Access: https://doi.org/10.1088/0004-6256/142/3/95

We report the discovery of HAT-P-31b, a transiting exoplanet orbiting the V = 11.660 dwarf star GSC 2099-00908. HAT-P-31b is the first planet discovered with the Hungarian-made Automated Telescope (HAT) without any follow-up photometry, demonstrating the feasibility of a new mode of operation for the HATNet project. The 2.17 M_J , 1.1 R_J planet has a period of P_b = 5.0054 days and maintains an unusually high eccentricity of e_b = 0.2450 ± 0.0045, determined through Keck, FIbr-fed Échelle Spectrograph, and Subaru high-precision radial velocities (RVs). Detailed modeling of the RVs indicates an additional quadratic residual trend in the data detected to very high confidence. We interpret this trend as a long-period outer companion, HAT-P-31c, of minimum mass 3.4 M_J and period ≥2.8 years. Since current RVs span less than half an orbital period, we are unable to determine the properties of HAT-P-31c to high confidence. However, dynamical simulations of two possible configurations show that orbital stability is to be expected. Further, if HAT-P-31c has non-zero eccentricity, our simulations show that the eccentricity of HAT-P-31b is actively driven by the presence of c, making HAT-P-31 a potentially intriguing dynamical laboratory. © 2011 The American Astronomical Society. Received 2011 June 6; accepted 2011 July 2; published 2011 August 16. Based in part on observations obtained at the W. M. Keck Observatory, which is operated by the University of California and the California Institute of Technology. Keck time has been granted by NASA (N167Hr). Based in part on data collected at Subaru Telescope, which is operated by the National Astronomical Observatory of Japan. Based in part on observations made with the Nordic Optical Telescope, operated on the island of La Palma jointly by Denmark, Finland, Iceland, Norway, and Sweden, in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias. HATNet operations have been funded by NASA grants NNG04GN74G, NNX08AF23G, and SAO ...