Kepler-10 c: a 2.2 Earth Radius Transiting Planet in a Multiple System

The Kepler mission has recently announced the discovery of Kepler-10 b, the smallest exoplanet discovered to date and the first rocky planet found by the spacecraft. A second, 45 day period transit-like signal present in the photometry from the first eight months of data could not be confirmed as being caused by a planet at the time of that announcement. Here we apply the light curve modeling technique known as BLENDER to explore the possibility that the signal might be due to an astrophysical false positive (blend). To aid in this analysis we report the observation of two transits with the Spitzer Space Telescope at 4.5 μm. When combined, they yield a transit depth of 344 ± 85 ppm that is consistent with the depth in the Kepler passband (376 ± 9 ppm, ignoring limb darkening), which rules out blends with an eclipsing binary of a significantly different color than the target. Using these observations along with other constraints from high-resolution imaging and spectroscopy, we are able to exclude the vast majority of possible false positives. We assess the likelihood of the remaining blends, and arrive conservatively at a false alarm rate of 1.6 × 10^(–5) that is small enough to validate the candidate as a planet (designated Kepler-10 c) with a very high level of confidence. The radius of this object is measured to be R_p = 2.227^(+0.052)_(–0.057) R_⊕ (in which the error includes the uncertainty in the stellar properties), but currently available radial-velocity measurements only place an upper limit on its mass of about 20 M_⊕. Kepler-10 c represents another example (with Kepler-9 d and Kepler-11 g) of statistical "validation" of a transiting exoplanet, as opposed to the usual "confirmation" that can take place when the Doppler signal is detected or transit timing variations are measured. It is anticipated that many of Kepler's smaller candidates will receive a similar treatment since dynamical confirmation may be difficult or impractical with the sensitivity of current instrumentation

Efficient evaluation of decoherence rates in complex Josephson circuits

A complete analysis of the decoherence properties of a Josephson junction qubit is presented. The qubit is of the flux type and consists of two large loops forming a gradiometer and one small loop, and three Josephson junctions. The contributions to relaxation (T_1) and dephasing (T_\phi) arising from two different control circuits, one coupled to the small loop and one coupled to a large loop, is computed. We use a complete, quantitative description of the inductances and capacitances of the circuit. Including two stray capacitances makes the quantum mechanical modeling of the system five dimensional. We develop a general Born-Oppenheimer approximation to reduce the effective dimensionality in the calculation to one. We explore T_1 and T_\phi along an optimal line in the space of applied fluxes; along this "S line" we see significant and rapidly varying contributions to the decoherence parameters, primarily from the circuit coupling to the large loop.Comment: 16 pages, 20 figures; v2: minor revisio

Gαq and its \u3ci\u3eAkt\u3c/i\u3eions

No abstract available

Device for selecting lightwave ranges via computer control for studying building material properties via goniophotometer

Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2007."June 2007."Includes bibliographical references (p. 21).To enable the fast and accurate cataloging of material samples, I designed a filtration device for selecting specific visible and near-infrared light wavelengths related to the red, green, and blue sensitivity peaks of a visible detection camera and the pixel response for a near-infrared camera. This filter device functions in conjunction with the Department of Architecture's Daylighting Laboratory goniophotometer to profile the complete reflection and transmission properties for sample building materials. The resulting data is used in computer simulations and material optimization. The goniophotometer uses two types of detection cameras, color and infrared, to measure the light that is transmitted or reflected off a sample of material. The spectral sensitivity variances of the cameras create inaccuracies in the resulting data when full-spectrum light is used. To remove these inaccuracies, the light is filtered into smaller sections of the full spectrum and the data is recombined by software, to remove these inaccuracies. The device to filter the light is the subject of this thesis. The final filter design uses a geneva drive to index wheels containing pairs of high-pass and low-pass filters into the light path between the light source and the test specimen.(cont.) The device satisfies the design specifications dictated by the usability, function and spatial constraints. This design should prove to be very reliable and flexible through its continued use in studying building materials. As the project is advanced, future work includes installation of the control system and integration into the software used to coordinate the goniophotometer components.by Timothy David Koch.S.B