* Astronomy

Title: Analysis of selected Kepler Mission planetary light curves
Author: M. D. Rhodes, E. Budding

We have modified the graphical user interfaced close binary system analysis program CurveFit to the form WinKepler and applied it to 16 representative planetary candidate light curves found in the NASA Exoplanet Archive (NEA) at the Caltech website this http URL, with an aim to compare different analytical approaches. WinKepler has parameter options for a realistic physical model, including gravity-brightening and structural parameters derived from the relevant Radau equation. We tested our best-fitting parameter-sets for formal determinacy and adequacy.
A primary aim is to compare our parameters with those listed in the NEA. Although there are trends of agreement, small differences in the main parameter values are found in some cases, and there may be some relative bias towards a 90 degrees value for the NEA inclinations. These are assessed against realistic error estimates.
Photometric variability from causes other than planetary transits affects at least 6 of the data-sets studied; with small pulsational behaviour found in 3 of those. For the false positive KOI 4.01, we found that the eclipses could be modelled by a faint background classical Algol as effectively as by a transiting exoplanet. Our empirical checks of limb-darkening, in the cases of KOI 1.01 and 12.01, revealed that the assigned stellar temperatures are probably incorrect. For KOI 13.01, our empirical mass-ratio differs by about 7% from that of Mislis and Hodgkin (2012), who neglected structural effects and higher order terms in the tidal distortion. Such detailed parameter evaluation, additional to the usual main geometric ones, provides an additional objective for this work.

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The planet-hunting career of NASA's Kepler spacecraft might be near its end.
Astronomers said Wednesday that a reaction wheel that keeps the orbiting telescope pointed at tiny, distant patches of sky to look for Earth-like planets, has failed. If they can't fix it, Kepler will be relegated to a less prestigious mission, directing its gaze much closer to home in a search for so-called "near-Earth objects", i.e., meteors and asteroids.
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Title: Objects in Kepler's Mirror May be Larger Than They Appear: Bias and Selection Effects in Transiting Planet Surveys
Authors: Eric Gaidos, Andrew W. Mann

Statistical analyses of large surveys for transiting planets such as the Kepler mission must account for systematic errors and biases. Transit detection depends not only on the planet's radius and orbital period, but also on host star properties. Thus, a sample of stars with transiting planets may not accurately represent the target population. Moreover, targets are selected using criteria such as a limiting apparent magnitude. These selection effects, combined with uncertainties in stellar radius, lead to biases in the properties of transiting planets and their host stars. We quantify possible biases in the Kepler survey. First, Eddington bias produced by a steep planet radius distribution and uncertainties in stellar radius results in a 15-20% overestimate of planet occurrence. Second, the magnitude limit of the Kepler target catalogue induces Malmquist bias towards large, more luminous stars and underestimation of the radii of about one third of candidate planets, especially those larger than Neptune. Third, because metal-poor stars are smaller, stars with detected planets will be very slightly (<0.02 dex) more metal-poor than the target average. Fourth, uncertainties in stellar radii produce correlated errors in planet radius and stellar irradiation. A previous finding, that highly-irradiated giant are more likely to have "inflated" radii, remains significant, even accounting for this effect. In contrast, transit depth is negatively correlated with stellar metallicity even in the absence of any intrinsic correlation, and a previous claim of a negative correlation between giant planet transit depth and stellar metallicity is probably an artifact.

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Kepler glitch may lower odds of finding Earth's twin

Our chances of finding an Earthlike planet any time soon may have just shrunk due to a glitch that could limit the lifetime of NASA's exoplanet-hunting spacecraft Kepler.
On 16 July, Kepler sent down data showing that one of its four reaction wheels, whose spin controls the probe's orientation, had stopped turning. Ground controllers shut down the malfunctioning wheel and briefly stopped gathering scientific data.
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