Spin orbit alignment for hot Jupiters KELT-7b and HAT-P-56b

Spin orbit alignment for KELT-7b and HAT-P-56b via Doppler tomography with TRES

Authors:

Zhou et al

Abstract:

We present Doppler tomographic analyses for the spectroscopic transits of KELT-7b and HAT-P-56b, two hot-Jupiters orbiting rapidly rotating F-dwarf host stars. These include analyses of archival TRES observations for KELT-7b, and a new TRES transit observation of HAT-P-56b. We report spin-orbit aligned geometries for KELT-7b (2.7 +/- 0.6 deg) and HAT-P-56b (8 +/- 2 deg). The host stars KELT-7 and HAT-P-56 are among some of the most rapidly rotating planet-hosting stars known. We examine the tidal re-alignment model for the evolution of the spin-orbit angle in the context of the spin rates of these stars. We find no evidence that the rotation rates of KELT-7 and HAT-P-56 have been modified by star-planet tidal interactions, suggesting that the spin-orbit angle of systems around these hot stars may represent their primordial configuration. In fact, KELT-7 and HAT-P-56 are two of three systems in super-synchronous, spin-orbit aligned states, where the rotation periods of the host stars are faster than the orbital periods of the planets.

HAT-P-56b: An Inflated Hot Jupiter Around an F Dwarf

An inflated massive Hot Jupiter transiting a bright F star followed up with K2.0 observations

Authors:

Huang et al

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 Mp≈2.18MJ, radius of Rp≈1.47RJ, and transits its host star on a near-grazing orbit with a period of P≈ 2.7908 d. The radius of HAT-P-56b is among the largest known for a planet with Mp>2MJ. The host star has a V-band magnitude of 10.9, mass of 1.30 M⊙, and radius of 1.43 R⊙. The periodogram of the K2 light curve suggests the star is a γ 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.