HAT-P-56b: An inflated massive Hot Jupiter transiting a bright F star followed up with K2 Campaign 0 observations

TL;DR

This paper reports the discovery and detailed characterization of HAT-P-56b, a massive, inflated hot Jupiter transiting a bright F star, combining ground-based and space-based observations for precise measurements.

Contribution

It presents the first combined ground and space-based observational analysis of HAT-P-56b, demonstrating the effectiveness of this approach for accurate exoplanet characterization.

Findings

HAT-P-56b has a mass of 2.18 M_J and a radius of 1.47 R_J.

The planet orbits its star every 2.7908 days on a near-grazing orbit.

The host star is a bright F-type star with V=10.9, showing γ Dor variability.

Abstract

We report the discovery of HAT-P-56b by the HATNet survey, an inflated hot Jupiter transiting a bright F type star in Field 0 of NASA's K2 mission. We combine ground-based discovery and follow-up light curves with high precision photometry from K2, as well as ground-based radial velocities from TRES on the FLWO 1.5m telescope to determine the physical properties of this system. HAT-P-56b has a mass of $2.18 M_J$, radius of $1.47 R_J$, and transits its host star on a near-grazing orbit with a period of 2.7908 d. The radius of HAT-P-56b is among the largest known for a planet with $M_p > 2 M_J$. The host star has a V-band magnitude of 10.9, mass of 1.30 $M_\odot$, and radius of 1.43 $R_\odot$. The periodogram of the K2 light curve suggests the star is a $\gamma$ Dor variable. HAT-P-56b is an example of a ground-based discovery of a transiting planet, where space-based observations greatly improve the confidence in the confirmation of its planetary nature, and also improve the accuracy of the planetary parameters.