Results 1 - 10 of 2402
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[en] The scientific objectives of the Galileo mission to the Jovian system is presented. Topics discussed include the history of the project, our current knowledge of the system, the objectives of interrelated experiments, mission design, spacecraft, and instruments. The management, scientists, and major contractors for the project are also given
[en] We present the discovery of a hot Jupiter transiting an F star in a close visual (0.''3 sky projected angular separation) binary system. The dilution of the host star's light by the nearly equal magnitude stellar companion (∼0.5 mag fainter) significantly affects the derived planetary parameters, and if left uncorrected, leads to an underestimate of the radius and mass of the planet by 10% and 60%, respectively. Other published exoplanets, which have not been observed with high-resolution imaging, could similarly have unresolved stellar companions and thus have incorrectly derived planetary parameters. Kepler-14b (KOI-98) has a period of P = 6.790 days and, correcting for the dilution, has a mass of Mp = 8.40+0.35-0.34 MJ and a radius of Rp = 1.136+0.073-0.054 RJ, yielding a mean density of ρp = 7.1 ± 1.1 g cm-3.
[en] Characteristics, description of surfaces and photographs of the Jupiter satellites, Io, Europa, Ganymede and Callisto, are presented. It is shown that the Gallilean satellites surfaces vary greatly: volcanos are found on the Io, extended light and dark bands are typical of the Europa smooth topology, the Ganymede has many craters and channels and the Callisto dotted with craters has large multiring basins
[en] We report on the discovery and confirmation of Kepler-7b, a transiting planet with unusually low density. The mass is less than half that of Jupiter, M P = 0.43 M J, but the radius is 50% larger, R P = 1.48 R J. The resulting density, ρP = 0.17 g cm-3, is the second lowest reported so far for an extrasolar planet. The orbital period is fairly long, P = 4.886 days, and the host star is not much hotter than the Sun, T eff = 6000 K. However, it is more massive and considerably larger than the Sun, M * = 1.35 M sun and R * = 1.84 R sun, and must be near the end of its life on the main sequence.
[en] The possible effects of non-gravitational forces on the motion of the comet P/Boethin are investigated for various values of the orbital period. A time interval of 2000 years backward and forward is treated. The authors find in all cases that the comet librates temporarily around the 1/1 resonance with Jupiter as a remote jovian satellite during at least two centuries. (Auth.)
[en] Hot Jupiters are expected to be dark from both observations (albedo upper limits) and theory (alkali metals and/or TiO and VO absorption). However, only a handful of hot Jupiters have been observed with high enough photometric precision at visible wavelengths to investigate these expectations. The NASA Kepler mission provides a means to widen the sample and to assess the extent to which hot Jupiter albedos are low. We present a global analysis of Kepler-7 b based on Q0-Q4 data, published radial velocities, and asteroseismology constraints. We measure an occultation depth in the Kepler bandpass of 44 ± 5 ppm. If directly related to the albedo, this translates to a Kepler geometric albedo of 0.32 ± 0.03, the most precise value measured so far for an exoplanet. We also characterize the planetary orbital phase light curve with an amplitude of 42 ± 4 ppm. Using atmospheric models, we find it unlikely that the high albedo is due to a dominant thermal component and propose two solutions to explain the observed planetary flux. First, we interpret the Kepler-7 b albedo as resulting from an excess reflection over what can be explained solely by Rayleigh scattering, along with a nominal thermal component. This excess reflection might indicate the presence of a cloud or haze layer in the atmosphere, motivating new modeling and observational efforts. Alternatively, the albedo can be explained by Rayleigh scattering alone if Na and K are depleted in the atmosphere by a factor of 10-100 below solar abundances.
[en] We announce the discovery of Kepler-6b, a transiting hot Jupiter orbiting a star with unusually high metallicity, [Fe/H]= +0.34±0.04. The planet's mass is about 2/3 that of Jupiter, M P = 0.67 M J, and the radius is 30% larger than that of Jupiter, R P = 1.32 R J, resulting in a density of ρP = 0.35 g cm-3, a fairly typical value for such a planet. The orbital period is P = 3.235 days. The host star is both more massive than the Sun, M * = 1.21 M sun, and larger than the Sun, R * = 1.39 R sun.
[en] We propose a high-contrast coronagraph for direct imaging of young Jupiter-like planets orbiting nearby bright stars. The coronagraph employs a step-transmission filter in which the intensity is apodized with a finite number of steps with identical transmission in each step. It should be installed on a large ground-based telescope equipped with a state-of-the-art adaptive optics system. In this case, contrast ratios around 10-6 should be accessible within 0.1 arcsec of the central star. In recent progress, a coronagraph with a circular apodizing filter has been developed, which can be used for a ground-based telescope with a central obstruction and spider structure. It is shown that ground-based direct imaging of Jupiter-like planets is promising with current technology.
[en] The equations of hydrodynamics for an ideal incompressible fluid are solved to give a simply connected Possby vortex (solitary wave) that would develop in zonal plane flow with velocity shear. The resulting solution is qualitatively consistent with the properties of the Great Red Spot on Jupiter