HAT-P-54b: A Hot Jupiter Transiting a 0.64 M_⊙ Star in field 0 of the K2 Mission

Creators: Bakos, G. Á.; Hartman, J. D.; Bhatti, W.; Bieryla, A.; de Val-Borro, M.; Latham, D. W.; Buchhave, L. A.; Csubry, Z.; Penev, K.; Kovács, G.; Béky, B.; Falco, E.; Kovács, T.; Howard, A. W.; Johnson, J. A.; Isaacson, H.; Marcy, G. W.; Torres, G.; Noyes, R. W.; Berlind, P.; Calkins, M. L.; Esquerdo, G. A.; Lázár, J.; Papp, I.; Sarin, P.

Abstract

We report the discovery of HAT-P-54b, a planet transiting a late K dwarf star in field 0 of the NASA K2 mission. We combine ground-based photometric light curves with radial velocity measurements to determine the physical parameters of the system. HAT-P-54b has a mass of 0.760 ± 0.032 M_J, a radius of 0.944 ± 0.028 R_J, and an orbital period of 3.7998 days. The star has V=13.505 ± 0.060, a mass of 0.645 ± 0.020 M_⊙, a radius of 0.617 ± 0.013 R_⊙, an effective temperature of T_(eff*) = 4390 ± 50, and a subsolar metallicity of [Fe/H] = -0.127 ± 0.080. We also detect a periodic signal with P = 15.6 days and 5.6 mmag amplitude in the light curve, which we interpret as due to the rotation of the star. HAT-P-54b has a radius that is smaller than 92% of the known transiting planets with masses greater than that of Saturn, while HAT-P-54 is one of the lowest-mass stars known to host a hot Jupiter. Follow-up high-precision photometric observations by the K2 mission promise to make this a well-studied planetary system.

Additional Information

© 2015. The American Astronomical Society. Received 2014 April 16. Accepted 2014 November 28. Published 2015 April 6. HATNet operations have been funded by NASA grants NNG04GN74G and NNX13AJ15G. Follow-up of HATNet targets has been partially supported through NSF grant AST-1108686. G.Á.B., Z.C., and K.P. acknowledge partial support from NASA grant NNX09AB29G. K.P. acknowledges support from NASA grant NNX13AQ62G. G.T. acknowledges partial support from NASA grant NNX14AB83G. We acknowledge partial support also from the Kepler Mission under NASA Cooperative Agreement NCC2-1390 (D.W.L., PI). G.K. thanks the Hungarian Scientific Research Foundation (OTKA) for support through grant K-81373. 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 (N133Hr). Data presented in this paper are based on observations obtained at the HAT station at the Submillimeter Array of SAO, and the HAT station at the Fred Lawrence Whipple Observatory of SAO. Data are also based on observations with the Fred Lawrence Whipple Observatory 1.5 m and 1.2 m telescopes of SAO. The authors wish to recognize and acknowledge the very significant cultural role and reverence that the summit of Mauna Kea has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain.

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