835 research outputs found

    The PLATO End-to-End CCD Simulator -- Modelling space-based ultra-high precision CCD photometry for the assessment study of the PLATO Mission

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    The PLATO satellite mission project is a next generation ESA Cosmic Vision satellite project dedicated to the detection of exo-planets and to asteroseismology of their host-stars using ultra-high precision photometry. The main goal of the PLATO mission is to provide a full statistical analysis of exo-planetary systems around stars that are bright and close enough for detailed follow-up studies. Many aspects concerning the design trade-off of a space-based instrument and its performance can best be tackled through realistic simulations of the expected observations. The complex interplay of various noise sources in the course of the observations made such simulations an indispensable part of the assessment study of the PLATO Payload Consortium. We created an end-to-end CCD simulation software-tool, dubbed PLATOSim, which simulates photometric time-series of CCD images by including realistic models of the CCD and its electronics, the telescope optics, the stellar field, the pointing uncertainty of the satellite (or Attitude Control System [ACS] jitter), and all important natural noise sources. The main questions that were addressed with this simulator were the noise properties of different photometric algorithms, the selection of the optical design, the allowable jitter amplitude, and the expected noise budget of light-curves as a function of the stellar magnitude for different parameter conditions. The results of our simulations showed that the proposed multi-telescope concept of PLATO can fulfil the defined scientific goal of measuring more than 20000 cool dwarfs brighter than mV =11 with a precision better than 27 ppm/h which is essential for the study of earth-like exo-planetary systems using the transit method.Comment: 5 pages, submitted for the Proceedings of the 4th HELAS International Conference: Seismological Challenges for Stellar Structur

    Engage D2.1 Communication plan, website, and visual identity material

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    The purpose of this document, Deliverable 2.1, is to describe the dissemination plan, dissemination policy and initial dissemination products of the SESAR 2020 Exploratory Research action Engage, taking into account its specifications and the target audience. The following pages document the corresponding tasks involved in D2.1

    Size dependence of the photoinduced magnetism and long-range ordering in Prussian blue analog nanoparticles of rubidium cobalt hexacyanoferrate

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    Nanoparticles of rubidium cobalt hexacyanoferrate (Rbj_jCok_k[Fe(CN)6_6]ln_l \cdot nH2_2O) were synthesized using different concentrations of the polyvinylpyrrolidone (PVP) to produce four different batches of particles with characteristic diameters ranging from 3 to 13 nm. Upon illumination with white light at 5 K, the magnetization of these particles increases. The long-range ferrimagnetic ordering temperatures and the coercive fields evolve with nanoparticle size. At 2 K, particles with diameters less than approximately 10 nm provide a Curie-like magnetic signal.Comment: 10 pages, 6 figures in text, expanded text and dat

    The On/Off Nature of Star-Planet Interactions

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    Evidence suggesting an observable magnetic interaction between a star and its hot Jupiter appears as a cyclic variation of stellar activity synchronized to the planet's orbit. In this study, we monitored the chromospheric activity of 7 stars with hot Jupiters using new high-resolution echelle spectra collected with ESPaDOnS over a few nights in 2005 and 2006 from the CFHT. We searched for variability in several stellar activity indicators (Ca II H, K, the Ca II infrared triplet, Halpha, and He I). HD 179949 has been observed almost every year since 2001. Synchronicity of the Ca II H & K emission with the orbit is clearly seen in four out of six epochs, while rotational modulation with P_rot=7 days is apparent in the other two seasons. We observe a similar phenomenon on upsilon And, which displays rotational modulation (P_rot=12 days) in September 2005, in 2002 and 2003 variations appear to correlate with the planet's orbital period. This on/off nature of star-planet interaction (SPI) in the two systems is likely a function of the changing stellar magnetic field structure throughout its activity cycle. Variability in the transiting system HD 189733 is likely associated with an active region rotating with the star, however, the flaring in excess of the rotational modulation may be associated with its hot Jupiter. As for HD 179949, the peak variability as measured by the mean absolute deviation for both HD 189733 and tau Boo leads the sub-planetary longitude by 70 degrees. The tentative correlation between this activity and the ratio of Mpsini to the planet's rotation period, a quantity proportional to the hot Jupiter's magnetic moment, first presented in Shkolnik et al. 2005 remains viable. This work furthers the characterization of SPI, improving its potential as a probe of extrasolar planetary magnetic fields.Comment: Accepted for publication in the Astrophysical Journa

    Blue Dots Team Transits Working Group Review

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    Transiting planet systems offer an unique opportunity to observationally constrain proposed models of the interiors (radius, composition) and atmospheres (chemistry, dynamics) of extrasolar planets. The spectacular successes of ground-based transit surveys (more than 60 transiting systems known to-date) and the host of multi-wavelength, spectro-photometric follow-up studies, carried out in particular by HST and Spitzer, have paved the way to the next generation of transit search projects, which are currently ongoing (CoRoT, Kepler), or planned. The possibility of detecting and characterizing transiting Earth-sized planets in the habitable zone of their parent stars appears tantalizingly close. In this contribution we briefly review the power of the transit technique for characterization of extrasolar planets, summarize the state of the art of both ground-based and space-borne transit search programs, and illustrate how the science of planetary transits fits within the Blue Dots perspective.Comment: 9 pages, 3 figures, to be published in the proceedings (ASP Conf. Ser.) of the "Pathways Towards Habitable Planets" conference, held in Barcelona (14-18 Sep 2009

    La confrontación de derechos en los escraches

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    Abstract:The recent practice of «escraches» in Spain, in the context of theeconomic crisis, has raised a complex debate about the confrontationbetween fundamental rights. Indeed, on one hand, it must be taken into account the right to free exercise of public office as well as personality rights (integrity, private and family life and peaceful enjoyment of the home) when not acting as a public representative.On the other hand, it must be taken in consideration the exercise of other fundamental rights (expression, demonstration) by those who perform escraches. This paper intends to analyze the conflicts between these fundamental rights in order to provide balanced responses, which lead to the following conclusion: «no» to escrache and «yes» to demostration.La reciente práctica de los escraches en España, en el contexto de lacrisis económica, ha planteado un complejo debate en torno a la confrontaciónentre derechos fundamentales. En efecto, de un lado, debetenerse en cuenta el derecho al libre ejercicio de un cargo público ylos derechos de la personalidad (integridad, vida privada y familiaro disfrute pacífico del domicilio) cuando no se actúa en calidad derepresentante público. De otro lado, debe tomarse en consideración elejercicio de otros derechos fundamentales (expresión, manifestación)por parte de quienes llevan a cabo los escraches. El presente trabajopretende analizar los conflictos entre esos derechos fundamentales conel fin de ofrecer unas respuestas ponderadas, las cuales concluyen conun «no» al escrache y un «sí» a la manifestación.Abstract:The recent practice of «escraches» in Spain, in the context of theeconomic crisis, has raised a complex debate about the confrontationbetween fundamental rights. Indeed, on one hand, it must be taken into account the right to free exercise of public office as well as personality rights (integrity, private and family life and peaceful enjoyment of the home) when not acting as a public representative.On the other hand, it must be taken in consideration the exercise of other fundamental rights (expression, demonstration) by those who perform escraches. This paper intends to analyze the conflicts between these fundamental rights in order to provide balanced responses, which lead to the following conclusion: «no» to escrache and «yes» to demostration.

    Magnetic cycles of the planet-hosting star Tau Bootis: II. a second magnetic polarity reversal

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    In this paper, we present new spectropolarimetric observations of the planet-hosting star Tau Bootis, using ESPaDOnS and Narval spectropolarimeters at Canada-France-Hawaii Telescope (CFHT) and Telescope Bernard Lyot (TBL), respectively. We detected the magnetic field of the star at three epochs in 2008. It is a weak magnetic field of only a few Gauss, oscillating between a predominant toroidal component in January and a dominant poloidal component in June and July. A magnetic polarity reversal was observed relative to the magnetic topology in June 2007. This is the second such reversal observed in two years on this star, suggesting that Tau Boo has a magnetic cycle of about 2 years. This is the first detection of a magnetic cycle for a star other than the Sun. The role of the close-in massive planet in the short activity cycle of the star is questioned. Tau Boo has strong differential rotation, a common trend for stars with shallow convective envelope. At latitude 40 deg., the surface layer of the star rotates in 3.31 d, equal to the orbital period. Synchronization suggests that the tidal effects induced by the planet may be strong enough to force at least the thin convective envelope into corotation. Tau Boo shows variability in the Ca H & K and Halpha throughout the night and on a night to night time scale. We do not detect enhancement in the activity of the star that may be related to the conjunction of the planet. Further data is needed to conclude about the activity enhancement due to the planet.Comment: 9 pages, 5 figures, 3 tables Accepted to MNRA

    Guest Editorial: Social and human aspects of cyber-physical systems

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    open6siIn the vision of Industry 4.0, the new industrial revolution is a revolution of cyber-physical systems, of which the Internet of Things forms a key foundation that has a great impact on the way people live, and the way businesses are organised. Cyber-physical systems are often considered feedback systems that integrate computation, networking, and physical processes, and more recently with ‘human-in-the-loop’ as one of the key research topics. The advances in social computing have connected human-inthe-loop in cyber-social systems such as Facebook and Twitter, while their social-physical activities are supported by the cyberphysical systems on or near their bodies and in their interconnected environments. Cyber-physical systems become an integral part of social-cyber-physical systems (SCPS) that weave into the sociotechnical fabric of human society. These hybrid systems, exhibiting both continuous (in physical and social spaces) and discrete (in cyberspaces) dynamic behaviour, give rise to not only new opportunities but also new challenges in designing products and services where human and technical aspects are massively intertwined. This Special Issue aims to present state-of-the-art research attempts and results on the topic of SCPS.openopenHu J.; Liang R.-H.; Shih C.-S.; Catala A.; Marcenaro L.; Osawa H.Hu, J.; Liang, R. -H.; Shih, C. -S.; CATALA MALLOFRE, Andreu; Marcenaro, L.; Osawa, H
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