2009ApJ...691.1145S

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 _–0.048M_☉, R_{*}= 0.829^+0.015_–0.022R_☉, and M_{*} = 1.404^+0.066_–0.134M_☉, R_{*}= 1.846^+0.096_–0.087R_☉ 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_–0.080M_Jup, R_p= 1.336^+0.031_–0.036R_Jupfor TrES-3, and M_p= 0.925±0.082 M_Jup, R_p= 1.783^+0.093_–0.086R _Jup for TrES-4. We confirm TrES-4 as the planet with the largest radius among the currently known transiting hot Jupiters.