A New Spectroscopic and Photometric Analysis of the Transiting Planet Systems TrES-3 and TrES-4

Abstract

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] $=-0.19\pm 0.08$, $T_{\mathrm{eff}}=5650\pm 75$ K, and $\log g=4.4\pm 0.1$ for TrES-3, and [Fe/H] $=+0.14\pm 0.09$, $T_{\mathrm{eff}}=6200\pm 75$ K, and $\log g=4.0\pm 0.1$ 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 $a/R_{\star }$ (related to the stellar density) in conjunction with our new temperatures and metallicities. The masses and radii we derive are $M_\star=0.928_{-0.048}^{+0.028} M_{\sun}$,$R_\star = 0.829_{-0.022}^{+0.015} R_{\sun}$, and $M_\star = 1.404_{-0.134}^{+0.066} M_{\sun}$, $R_\star=1.846_{-0.087}^{+0.096} R_{\sun}$ for TrES-3 and TrES-4, respectively. With these revised stellar parameters we obtain improved values for the planetary masses and radii. We find $M_p=1.910_{-0.080}^{+0.075}{M}_{\mathrm{Jup}}$, $R_p=1.336_{-0.036}^{+0.031}{R}_{\mathrm{Jup}}$ for TrES-3, and $M_p=0.925\pm 0.082M_{\mathrm{Jup}}$, $R_p=1.783_{-0.086}^{+0.093}{R}_{\mathrm{Jup}}$ for TrES-4. We confirm TrES-4 as the planet with the largest radius among the currently known transiting hot Jupiters.

42 pages, 10 tables, 8 figures. Accepted for publication in the Astrophysical Journal