CD Tau: a detached eclipsing binary with a solar-mass companion

We present a detailed analysis of the detached eclipsing binary CD Tau. A large variety of observational data, in form of IR photometry, CORAVEL radial velocity observations and high-resolution spectra, are combined with the published light curves to derive accurate absolute dimensions and effective temperature of the components, as well as the metal abundance of the system. We obtain: MA=1.442(16) Mo, RA=1.798(17) Ro, TeffA=6200(50) K, MB=1.368(16) Msun, RB=1.584(20) Run and TeffB=6200(50) K. The metal content of the system is determined to be [Fe/H]=+0.08(15) dex. In addition, the eclipsing binary has a K-type close visual companion at about 10-arcsec separation, which is shown to be physically linked, thus sharing a common origin. The effective temperature of the visual companion (Teff=5250(200) K) is determined from synthetic spectrum fitting, and its luminosity (log L/Lo=-0.27(6)), and therefore its radius (R=0.89(9) Ro), are obtained from comparison with the apparent magnitude of the eclipsing pair. The observed fundamental properties of the eclipsing components are compared with the predictions of evolutionary models, and we obtain good agreement for an age of 2.6 Gyr and a chemical composition of Z=0.026 and Y=0.26. Furthermore, we test the evolutionary models for solar-mass stars and we conclude that the physical properties of the visual companion are very accurately described by the same isochrone that fits the more massive components.Comment: 9 pages, 6 figures, accepted for publication in MNRA

Astrometric Light-Travel Time signature of sources in nonlinear motion

Context:Very precise planned space astrometric missions and recent improvements on imaging capabilities require a detailed review of the assumptions of classical astrometric modeling. Aims:We show that Light-Travel Time must be taken into account to model the kinematics of astronomical objects in nonlinear motion, even at stellar distances. Methods:A closed expression to include Light-Travel Time in the actual astrometric models with nonlinear motion is provided. Using a perturbative approach the expression of the Light-Travel Time signature is derived. We propose a practical form of the astrometric modelling to be applied in astrometric data reduction of sources at stellar distances($d>1 pc$). Results :We show that the Light-Travel Time signature is relevant at \muas accuracy (or even at $mas$) depending on the time span of the astrometric measurements. We explain how information about the radial motion of a source can be obtained. Some estimative numbers are provided for known nearby binary systems Conclusions :In the light of the obtained results, it is clear that this effect must be taken into account to interpret any kind of precise astrometric measurements. The effect is particularly interesting in measurements performed by the planned astrometric space missions (GAIA, SIM, JASMINE, TPF/DARWIN). Finally an objective criterion is provided to quickly evaluate whether the Light-Travel Time modeling is required for a given source or system.Comment: 10 pages, 2 figure

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An evolutionary algorithm to enhance multivariate Post-Randomization Method (PRAM) protections

The amount of public statistical information available is growing and more accurate protection methods are needed in order to achieve data confidentiality. The Post-Randomization Method (PRAM) protection method was introduced in 1997 as a very powerful method for categorical microdata, but it is still not widely used. This method has a Markov matrix as a parameter. The main problem of the application of this method is that it is difficult to find a good Markov matrix that performs changes in the microdata file producing low loss of valuable information and low risk of disclosure of sensitive data. In this paper we present a methodology that helps us to find a matrix to perform better protections. This is achieved by using an evolutionary algorithm with integrated Information Loss and Disclosure Risk measures. Experiments using three different datasets are also presented in order to empirically evaluate the application of this technique. © 2014 Elsevier Inc. All rights reserved.This work has been done under the PhD in Computer Science program of the Universitat Autònoma de Barcelona (UAB). It is also partially supported by the Spanish MEC ARES-CONSOLIDER INGENIO 2010 CSD2007-00004, and COPRIVACY TIN2011-27076-C03-03. The research leading to these results has also received funding from the European Union’s Seventh Framework Programme (FP7/2007-2013) under Grant Agreement Num. 262608.Peer Reviewe

Efficiency, profitability and carbon footprint of different management programs under no-till to control herbicide resistant Papaver rhoeas

The present work examines the effects of different integrated weed management (IWM) programs on multiple herbicide-resistant Papaver rhoeas populations in terms of effectiveness, profitability and carbon footprint. With this aim a trial was established in a winter cereal field under no-till in North-Eastern Spain during three consecutive seasons. Four IWM programs with different intensification levels, from less (crop rotation, mechanical control, and no herbicides) to more intense (wheat monoculture with high chemical inputs), were established. The different strategies integrated in the four programs were efficient in managing the weed after three years, with increased effectiveness after management program intensification. Whereas low input program (which includes fallow season) represented less economic cost than the other programs, on average, no differences were observed on carbon foot print, considered as kg CO2eq kg−1 product, between the different programs, except in the crop rotation program due to the low pea yield obtained. The results from this study show that in the search for a balance between crop profitability and reduction of the carbon footprint while controlling an herbicide resistant population is challenging, and particularly under notill. In this scenario the short term priority should be to reduce the presence of multiple herbicide resistant biotypes integrating the different available chemical, cultural, and physical strategies.This work has been supported by the Agencia Estatal de Investigación (AEI) and the European Regional Development Fund (ERDF) with project AGL2014-52465-C4-2-R. Dr. J. Torra obtained a Ramon y Cajal contract from the Spanish Ministry of Science, Innovation and Universities (RYC2018-023866-I). Mr. F. Valencia-Gredilla obtained a PhD grant from the University of Lleida