We report the detection of a transiting Jupiter-sized planet orbiting a relatively bright ( ) K0 V star. V p 11.79 We detected the transit light-curve signature in the course of the TrES multisite transiting planet survey and confirmed the planetary nature of the companion via multicolor photometry and precise radial velocity measurements. We designate the planet TrES-1; its inferred mass is , its radius is ,Ϫ0.04 Jup and its orbital period is days. This planet has an orbital period similar to that of HD 3.030065 ‫ע‬ 0.000008 209458b but about twice as long as those of the OGLE transiting planets. Its mass is indistinguishable from that of HD 209458b, but its radius is significantly smaller and fits the theoretical models without the need for an additional source of heat deep in the atmosphere, as has been invoked by some investigators for HD 209458b.

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 -2with 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.

We announce the discovery of the second transiting hot Jupiter discovered by the Transatlantic Exoplanet Survey. The planet, which we dub TrES-2, orbits the nearby star GSC 03549-02811 every 2.47063 days. From highresolution spectra, we determine that the star has and , implying a spectral T p 5960 ‫ע‬ 100 K log g p 4.4 ‫ע‬ 0.2 eff type of G0 V and a mass of. High-precision radial velocity measurements confirm a sinusoidal variation ϩ0.11 1.08 M Ϫ0.05 , with the period and phase predicted by the photometry, and rule out the presence of line bisector variations that would indicate that the spectroscopic orbit is spurious. We estimate a planetary mass of. We model ϩ0.09 1.28 M Ϫ0.04 Jup B, r, R, and I photometric time series of the 1.4% deep transits and find a planetary radius of. This ϩ0.09 1.24 R Ϫ0.06 Jup planet lies within the field of view of the NASA Kepler mission, ensuring that hundreds of upcoming transits will be monitored with exquisite precision and permitting a host of unprecedented investigations. Subject headings: planetary systems-stars: individual (GSC 03549-02811)-techniques: photometrictechniques: radial velocities 1 Some of the data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among Caltech, the University of California, and NASA. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation.

We report the discovery of TrES-4, a hot Jupiter that transits the star GSC 02620-00648 every 3.55 days. From high-resolution spectroscopy of the star, we estimate a stellar effective temperature of K, and T p 6100 ‫ע‬ 150 eff from high-precision z and B photometry of the transit we constrain the ratio of the semimajor axis a and the stellar radius to be . We compare these values to model stellar isochrones to constrain the stellar R a/R p 6.03 ‫ע‬ 0.13 * * mass to be . Based on this estimate and the photometric time series, we constrain the stellar M p 1.22 ‫ע‬ 0.17 M * , radius to be and the planet radius to be . We model our radial R p 1.738 ‫ע‬ 0.092 R R p 1.674 ‫ע‬ 0.094 R * , p Jup velocity data assuming a circular orbit and find a planetary mass of . Our radial velocity observations 0.84 ‫ע‬ 0.10 M Jup rule out line-bisector variations that would indicate a specious detection resulting from a blend of an eclipsing binary system. TrES-4 has the largest radius and lowest density of any of the known transiting planets. It presents a challenge to current models of the physical structure of hot Jupiters and indicates that the diversity of physical properties among the members of this class of exoplanets has yet to be fully explored.

No abstract