A NEW SPECTROSCOPIC AND PHOTOMETRIC ANALYSIS OF THE TRANSITING PLANET SYSTEMS TrES-3 AND TrES-4

We report new spectroscopic and photometric observations of the parent stars of the recently discovered transiting planets TrES-3 and TrES-4. A detailed abundance analysis based on high-resolution spectra yields [Fe/H] = −0.19 ± 0.08, T eff = 5650 ± 75 K, and log g = 4.4 ± 0.1 for TrES-3, and [Fe/H] = +0.14 ± 0.09, T eff = 6200 ± 75 K, and log g = 4.0 ± 0.1 for TrES-4. The accuracy of the effective temperatures is supported by a number of independent consistency checks. The spectroscopic orbital solution for TrES-3 is improved with our new radial velocity measurements of that system, as are the light-curve parameters for both systems based on newly acquired photometry for TrES-3 and a reanalysis of existing photometry for TrES-4. We have redetermined the stellar parameters taking advantage of the strong constraint provided by the light curves in the form of the normalized separation a / R ⋆ (related to the stellar density) in conjunction with our new temperatures and metallicities. The masses and radii we derive are M ⋆ = 0.928 +0.028 −0.048 M ☉ , R ⋆ = 0.829 +0.015 −0.022 R ☉ , and M ⋆ = 1.404 +0.066 −0.134 M ☉ , R ⋆ = 1.846 +0.096 −0.087 R ☉ for TrES-3 and TrES-4, respectively. With these revised stellar parameters, we obtain improved values for the planetary masses and radii. We find M p = 1.910 +0.075 −0.080 M Jup , R p = 1.336 +0.031 −0.036 R Jup for TrES-3, and M p = 0.925 ± 0.082 M Jup , R p = 1.783 +0.093 −0.086 R Jup for TrES-4. We confirm TrES-4 as the planet with the largest radius among the currently known transiting hot Jupiters.