High-Resolution Spectroscopy of the Transiting Planet Host Star TrES-1
  We report on a spectroscopic determination of the stellar parameters and chemical abundances for the parent star of the transiting planet TrES-1. Based on a detailed analysis of iron lines in our Keck and HET spectra we derive $T_\mathrm{eff} = 5250\pm 75$ K, $\log g = 4.6\pm 0.2$, and [Fe/H] $= 0.00\pm 0.09$. By measuring the \ion{Ca}{2} activity indicator and by putting useful upper limits on the Li abundance we constrain the age of TrES-1 to be $2.5\pm 1.5$ Gyr. By comparing theoretical stellar evolution models with the observational parameters we obtain $M_\star = 0.89\pm 0.05$ $M_\odot$, and $R_\star = 0.83\pm 0.05$ $R_\odot$. Our improved estimates of the stellar parameters are utilized in a new analysis of the transit photometry of TrES-1 to derive a mass $M_p = 0.76\pm 0.05$ $M_\mathrm{J}$, a radius $R_p = 1.04^{+0.08}_{-0.05}$ $R_\mathrm{J}$, and an inclination $i = 89^\circ.5^{+0.5}_{-1.3}$. The improved planetary mass and radius estimates provide the grounds for new crucial tests of theoretical models of evolution and evaporation of irradiated extrasolar giant planets. 
A. Sozzetti (1,2), D. Yong (3), G. Torres (2), D. Charbonneau (2), D.   W. Latham (2), C. A. Prieto (4), T. M. Brown (5), B....