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arXiv · 1606.00848

HATS-18 b: An Extreme Short--Period Massive Transiting Planet Spinning Up Its Star

Kaloyan M. Penev·Joel D. Hartman·Gaspar A. Bakos·Simona Ciceri·Rafael Brahm·Daniel Bayliss·Joao Bento·Andr'es Jord'an·Zoltan Csubry·W. Bhatti·Miguel de Val-Borro·Néstor Espinoza·George Zhou·Luigi Mancini·Markus Rabus·Vincent Suc·Thomas Henning·Brian P. Schmidt·Robert W. Noyes·J. L'az'ar·Istvan Papp·P. S'ari
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Abstract

We report the discovery by the HATSouth network of HATS-18 b: a 1.980 +/- 0.077 Mj, 1.337 +0.102 -0.049 Rj planet in a 0.8378 day orbit, around a solar analog star (mass 1.037 +/- 0.047 Msun, and radius 1.020 +0.057 -0.031 Rsun) with V=14.067 +/- 0.040 mag. The high planet mass, combined with its short orbital period, implies strong tidal coupling between the planetary orbit and the star. In fact, given its inferred age, HATS-18 shows evidence of significant tidal spin up, which together with WASP-19 (a very similar system) allows us to constrain the tidal quality factor for Sun-like stars to be in the range 6.5 <= lg(Q*/k_2) <= 7 even after allowing for extremely pessimistic model uncertainties. In addition, the HATS-18 system is among the best systems (and often the best system) for testing a multitude of star--planet interactions, be they gravitational, magnetic or radiative, as well as planet formation and migration theories.

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Kaloyan M. Penev, Joel D. Hartman, Gaspar A. Bakos, Simona Ciceri, Rafael Brahm, Daniel Bayliss, Joao Bento, Andr'es Jord'an, Zoltan Csubry, W. Bhatti, Miguel de Val-Borro, Néstor Espinoza, George Zhou, Luigi Mancini, Markus Rabus, Vincent Suc, Thomas Henning, Brian P. Schmidt, Robert W. Noyes, J. L'az'ar, Istvan Papp, P. S'ari. 2016-06-02. HATS-18 b: An Extreme Short--Period Massive Transiting Planet Spinning Up Its Star. https://doi.org/10.3847/0004-6256%2F152%2F5%2F127

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