Variability survey in the CoRoT SRa01 field: Implications of eclipsing binary distribution on cluster formation in NGC 2264

Time-series photometry of the CoRoT field SRa01 was carried out with the Berlin Exoplanet Search Telescope II (BEST II) in 2008/2009. A total of 1,161 variable stars were detected, of which 241 were previously known and 920 are newly found. Several new, variable young stellar objects have been discovered. The study of the spatial distribution of eclipsing binaries revealed the higher relative frequency of Algols toward the center of the young open cluster NGC 2264. In general Algol frequency obeys an isotropic distribution of their angular momentum vectors, except inside the cluster, where a specific orientation of the inclinations is the case. We suggest that we see the orbital plane of the binaries almost edge-on.Comment: 18 pages, 8 figures, accepted for publication in Ap

Structure and dynamics of a model glass: influence of long-range forces

We vary the amplitude of the long-range Coulomb forces within a classical potential describing a model silica glass and study the consequences on the structure and dynamics of the glass, via molecular dynamics simulations. This model allows us to follow the variation of specific features such as the First Sharp Diffraction Peak and the Boson Peak in a system going continuously from a fragile (no Coulomb forces) to a strong (with Coulomb forces) glass. In particular we show that the characteristic features of a strong glass (existence of medium range order, bell-shaped ring size distribution, sharp Boson peak) appear as soon as tetrahedral units are formed.Comment: 5 pages, 4 figures. To be published in J.Phys.: C

The Berlin Exoplanet Search Telescope II. Catalog of Variable Stars. I. Characterization of Three Southern Target Fields

A photometric survey of three Southern target fields with BEST II yielded the detection of 2,406 previously unknown variable stars and an additional 617 stars with suspected variability. This study presents a catalog including their coordinates, magnitudes, light curves, ephemerides, amplitudes, and type of variability. In addition, the variability of 17 known objects is confirmed, thus validating the results. The catalog contains a number of known and new variables that are of interest for further astrophysical investigations, in order to, e.g., search for additional bodies in eclipsing binary systems, or to test stellar interior models. Altogether, 209,070 stars were monitored with BEST II during a total of 128 nights in 2009/2010. The overall variability fraction of 1.2-1.5% in these target fields is well comparable to similar ground-based photometric surveys. Within the main magnitude range of $R\in\left[11,17\right]$, we identify 0.67(3)% of all stars to be eclipsing binaries, which indicates a completeness of about one third for this particular type in comparison to space surveys.Comment: accepted to A

The Opinion-Policy Nexus in Europe and the Role of Political Institutions

A strong link between citizen preferences and public policy is one of the key goals and criteria of democratic governance. Yet, our knowledge about the extent to which public policies on specific issues are in line with citizen preferences in Europe is limited. This article reports on the first study of the link between public opinion and public policy that covers a large and diverse sample of concrete public policy issues in 31 European democracies. The findings demonstrate a strong positive relationship and a substantial degree of congruence between public opinion and the state of public policy. Also examined is whether political institutions, including electoral systems and the horizontal and vertical division of powers, influence the opinion‐policy link. The evidence for such effects is very limited, which suggests that the same institutions might affect policy representation in countervailing ways through different mechanisms

Pre-discovery observations of CoRoT-1b and CoRoT-2b with the BEST survey

The BEST wide-angle telescope installed at the Observatoire de Haute-Provence and operated in remote control from Berlin by the Institut fuer Planetenforschung, DLR, has observed the CoRoT target fields prior to the mission. The resulting archive of stellar photometric lightcurves is used to search for deep transit events announced during CoRoT's alarm-mode to aid in fast photometric confirmation of these events. The "initial run" field of CoRoT (IRa01) has been observed with BEST in November and December 2006 for 12 nights. The first "long run" field (LRc01) was observed from June to September 2005 for 35 nights. After standard CCD data reduction, aperture photometry has been performed using the ISIS image subtraction method. About 30,000 lightcurves were obtained in each field. Transits of the first detected planets by the CoRoT mission, CoRoT-1b and CoRoT-2b, were found in archived data of the BEST survey and their lightcurves are presented here. Such detections provide useful information at the early stage of the organization of follow-up observations of satellite alarm-mode planet candidates. In addition, no period change was found over ~4 years between the first BEST observation and last available transit observations.Comment: AJ, accepte

Cumulative and Differential Effects of Early Child Care and Middle Childhood Out-of-School Time on Adolescent Functioning.

Effects associated with early child care and out-of-school time (OST) during middle childhood were examined in a large sample of U.S. adolescents (N = 958). Both higher quality early child care AND more epochs of organized activities (afterschool programs and extracurricular activities) during middle childhood were linked to higher academic achievement at age 15. Differential associations were found in the behavioral domain. Higher quality early child care was associated with fewer externalizing problems, whereas more hours of early child care was linked to greater impulsivity. More epochs of organized activities was associated with greater social confidence. Relations between early child care and adolescent outcomes were not mediated or moderated by OST arrangements in middle childhood, consistent with independent, additive relations of these nonfamilial settings

The NASA 2D wall-mounted hump simulated using DDES-SA with the G3D::Flow solver

With the interest in simulating complex geometries using the Delayed Detached Eddy Simulation (DDES) model, an initial step should be taken in verifying the methodologies needed. The DDES model is used with a newly proposed modification to the sub-grid length-scale, the shear-layer-adaptive length-scale, to improve the transition from RANS to LES. The well-known 2D NASA wall-mounted hump test case is simulated. RANS simulations are performed to verify a correct implementation of the turbulence model developed by Spalart and Allmaras (SA). The SA model is important as it will serve as the underlying sub-grid-scale model for the DDES. Furthermore, RANS was used in an initial grid study. Two simulations are performed using the DDES model, where the difference lies in the number of cells and the grid topology. The results show an extended steady shear-layer in the separated region, delaying the transition from RANS to LES, where the cause is suggested to be insufficient grid resolution in the focus region. This influences the prediction of the re-attachment location and the velocity profiles downstream of the hump. However, one of the transient simulations improves the predictions of the re-attachment location and downstream velocity profiles. The other transient simulation is, however, not capable of improving the RANS results due to the delayed breakdown of two-dimensional coherent structures generated at the separation location. The results from the two DDES simulations indicate that the grid-resolution near the separation point needs refinement for a faster transition from RANS to LES. Using an explicit CFD solver for transient simulations of wall-bounded flow configurations, special treatment is needed to make the time-step requirements restricted by flow physics, rather than the numerical stability-limit. To achieve this, the dual-time stepping method has been implemented in to the in-house CFD solver, G3D::Flow. When using the dual-time stepping method, in combination with residual smoothing and low-speed reconditioning, a speed-up of approximately 50 is achieved

Noise properties of the CoRoT data: a planet-finding perspective

In this short paper, we study the photometric precision of stellar light curves obtained by the CoRoT satellite in its planet finding channel, with a particular emphasis on the timescales characteristic of planetary transits. Together with other articles in the same issue of this journal, it forms an attempt to provide the building blocks for a statistical interpretation of the CoRoT planet and eclipsing binary catch to date. After pre-processing the light curves so as to minimise long-term variations and outliers, we measure the scatter of the light curves in the first three CoRoT runs lasting more than 1 month, using an iterative non-linear filter to isolate signal on the timescales of interest. The bevhaiour of the noise on 2h timescales is well-described a power-law with index 0.25 in R-magnitude, ranging from 0.1mmag at R=11.5 to 1mmag at R=16, which is close to the pre-launch specification, though still a factor 2-3 above the photon noise due to residual jitter noise and hot pixel events. There is evidence for a slight degradation of the performance over time. We find clear evidence for enhanced variability on hours timescales (at the level of 0.5 mmag) in stars identified as likely giants from their R-magnitude and B-V colour, which represent approximately 60 and 20% of the observed population in the direction of Aquila and Monoceros respectively. On the other hand, median correlated noise levels over 2h for dwarf stars are extremely low, reaching 0.05mmag at the bright end.Comment: 5 pages, 4 figures, accepted for publication in A&

Removing systematics from the CoRoT light curves: I. Magnitude-Dependent Zero Point

This paper presents an analysis that searched for systematic effects within the CoRoT exoplanet field light curves. The analysis identified a systematic effect that modified the zero point of most CoRoT exposures as a function of stellar magnitude. We could find this effect only after preparing a set of learning light curves that were relatively free of stellar and instrumental noise. Correcting for this effect, rejecting outliers that appear in almost every exposure, and applying SysRem, reduced the stellar RMS by about 20 %, without attenuating transit signals.Comment: Accepted for publication in Astronomy and Astrophysic