TrES-5: A Massive Jupiter-sized Planet Transiting A Cool G-dwarf

TL;DR

The paper reports the discovery and characterization of TrES-5, a massive hot Jupiter transiting a relatively faint G-dwarf star, demonstrating the feasibility of ground-based detection and follow-up for such faint targets.

Contribution

First detailed characterization of TrES-5, a massive hot Jupiter orbiting a faint star, showing ground-based transit detection is feasible for faint stars.

Findings

Planet radius: 1.209 Jupiter radii

Planet mass: 1.778 Jupiter masses

Orbital period: 1.48 days

Abstract

We report the discovery of TrES-5, a massive hot Jupiter that transits the star GSC 03949-00967 every 1.48 days. From spectroscopy of the star we estimate a stellar effective temperature of$5171 +/- 36 K, and from high-precision B, R and I photometry of the transit we constrain the ratio of the semi-major axis and the stellar radius to be 6.07 +/- 0.14. We compare these values to model stellar isochrones to obtain a stellar mass of 0.893 +/- 0.024 solar masses. Based on this estimate and the photometric time series, we constrain the stellar radius to be 0.866 +/- 0.013 solar radii, and the planet radius to be 1.209 +/- 0.021 Jupiter radii. We model our radial-velocity data assuming a circular orbit and find a planetary mass of 1.778 +/- 0.063 Jupiter masses. Our radial-velocity observations rule out line-bisector variations that would indicate a specious detection resulting from a blend of an eclipsing binary system. TrES-5 orbits one of the faintest stars with transiting planets found to date from the ground and demonstrates that precise photometry and followup spectroscopy are possible, albeit challenging, even for such faint stars.