arXiv subjects

Alessandro Sozzetti

Publications and source records attributed to Alessandro Sozzetti.

95 records · Page 6Linked to original sources

arXiv2007

TrES-3: A Nearby, Massive, Transiting Hot Jupiter in a 31-Hour Orbit

We describe the discovery of a massive transiting hot Jupiter with a very short orbital period (1.30619 d), which we name TrES-3. From spectroscopy of the host star GSC 03089-00929, we measure T_eff = 5720 +- 150 K, logg=4.6 +- 0.3, and vsini < 2 km/s, and derive a stellar mass of 0.90 +- 0.15 M_sun. We estimate a planetary mass of 1.92 +- 0.23 M_Jup, based on the sinusoidal variation of our high-precision radial velocity measurements. This variation has a period and phase consistent with our transit photometry. Our spectra show no evidence of line bisector variations that would indicate a blended eclipsing binary star. From detailed modeling of our B and z photometry of the 2.5%-deep transits, we determine a stellar radius 0.802 +- 0.046 R_sun and a planetary radius 1.295 +- 0.081 R_Jup. TrES-3 has one of the shortest orbital periods of the known transiting exoplanets, facilitating studies of orbital decay and mass loss due to evaporation, and making it an excellent target for future studies of infrared emission and reflected starlight.

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arXiv2007

The Transit Light Curve Project. VI. Three Transits of the Exoplanet TrES-2

Of the nearby transiting exoplanets that are amenable to detailed study, TrES-2 is both the most massive and has the largest impact parameter. We present z-band photometry of three transits of TrES-2. We improve upon the estimates of the planetary, stellar, and orbital parameters, in conjunction with the spectroscopic analysis of the host star by Sozzetti and co-workers. We find the planetary radius to be 1.222 +/- 0.038 R_Jup and the stellar radius to be 1.003 +/- 0.027 R_Sun. The quoted uncertainties include the systematic error due to the uncertainty in the stellar mass (0.980 +/- 0.062 M_Sun). The timings of the transits have an accuracy of 25s and are consistent with a uniform period, thus providing a baseline for future observations with the NASA Kepler satellite, whose field of view will include TrES-2.

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arXiv2006

TrES-2: The First Transiting Planet in the Kepler Field

We announce the discovery of the second transiting hot Jupiter discovered by the Trans-atlantic Exoplanet Survey. The planet, which we dub TrES-2, orbits the nearby star GSC 03549-02811 every 2.47063 days. From high-resolution spectra, we determine that the star has T_eff = 5960 +/- 100 K and log(g) = 4.4 +/- 0.2, implying a spectral type of G0V and a mass of 1.08 +0.11/-0.05 M_sun. High-precision radial-velocity measurements confirm a sinusoidal variation 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 1.28 +0.09/-0.04 M_Jup. We model B, r, R, and I photometric timeseries of the 1.4%-deep transits and find a planetary radius of 1.24 +0.09/-0.06 R_Jup. This 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.

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arXiv2005

Detection of Thermal Emission from an Extrasolar Planet

We present Spitzer Space Telescope infrared photometric time series of the transiting extrasolar planet system TrES-1. The data span a predicted time of secondary eclipse, corresponding to the passage of the planet behind the star. In both bands of our observations, we detect a flux decrement with a timing, amplitude, and duration as predicted by published parameters of the system. This signal represents the first direct detection of (i.e. the observation of photons emitted by) a planet orbiting another star. The observed eclipse depths (in units of relative flux) are 0.00066 +/- 0.00013 at 4.5um and 0.00225 +/- 0.00036 at 8.0um. These estimates provide the first observational constraints on models of the thermal emission of hot Jupiters. Assuming that the planet emits as a blackbody, we estimate an effective temperature of T_p=1060 +/- 50 K. Under the additional assumptions that the planet is in thermal equilibrium with the radiation from the star and emits isotropically, we find a Bond albedo of A = 0.31 +/- 0.14. This would imply that the planet absorbs the majority of stellar radiation incident upon it, a conclusion of significant impact to atmospheric models of these objects. We compare our data to a previously-published model of the planetary thermal emission, which predicts prominent spectral features in our observational bands due to water and carbon monoxide. Based on the time of secondary eclipse, we present an upper limit on the orbital eccentricity that is sufficiently small that we conclude that tidal dissipation is unlikely to provide a significant source of energy interior to the planet.(abridged)

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arXiv2004

TrES-1: The Transiting Planet of a Bright K0V Star

We report the detection of a transiting Jupiter-sized planet orbiting a relatively bright (V=11.79) K0V star. We detected the transit light-curve signature in the course of the TrES multi-site 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 0.75 +/- 0.07 Jupiter masses, its radius is 1.08 (+0.18/-0.04) Jupiter radii, and its orbital period is 3.030065 +/- 0.000008 days. This planet has an orbital period similar to that of HD 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.

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