165 research outputs found

    Olvidar o asumir el pasado : Los españoles y la memoria

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    En 1999, el gobierno español y el Congreso de los Diputados se negaron a condenar el « Levantamiento Nacional » de 1936. Esta toma de posición provocó en España numerosas reacciones de amplios sectores de la opinión. La publicación, el 26-6-1999, por El País de un artículo del novelista Javier Marías, abrió en las columnas de este diario un amplio debate sobre la oportunidad para los españoles de olvidar o de asumir el pasado inmediato. Desde aquella fecha, otros tres intelectuales han venido publicando artículos, ampliando así la reflexión. Pero lo me pareció sumamente interesante es que para prolongar este tema, El País abrió un debate en un foro de discusión de la edición por Internet del diario. Hasta mediados de abril 2000, fecha del cierre de este foro he seguido los debates con mucha atención y he podido registrar 119 contribuciones, representando algo más de 80 páginas de opiniones sobre el tema. El trabajo que presento en las líneas que siguen es el resultado del análisis de las opiniones emitidas, pero al tratarse de la explotación de un material recogido por Internet, es decir algo que me parece bastante nuevo, me parece importante empezar por esbozar unas cuantas reflexiones en cuanto a la validez que pueda tener este material para un historiador. Me parece también interesante aludir a los métodos de trabajo elegidos y a los resultados globales antes de pasar al tema de fondo.Facultad de Humanidades y Ciencias de la Educació

    Olvidar o asumir el pasado : Los españoles y la memoria

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    En 1999, el gobierno español y el Congreso de los Diputados se negaron a condenar el « Levantamiento Nacional » de 1936. Esta toma de posición provocó en España numerosas reacciones de amplios sectores de la opinión. La publicación, el 26-6-1999, por El País de un artículo del novelista Javier Marías, abrió en las columnas de este diario un amplio debate sobre la oportunidad para los españoles de olvidar o de asumir el pasado inmediato. Desde aquella fecha, otros tres intelectuales han venido publicando artículos, ampliando así la reflexión. Pero lo me pareció sumamente interesante es que para prolongar este tema, El País abrió un debate en un foro de discusión de la edición por Internet del diario. Hasta mediados de abril 2000, fecha del cierre de este foro he seguido los debates con mucha atención y he podido registrar 119 contribuciones, representando algo más de 80 páginas de opiniones sobre el tema. El trabajo que presento en las líneas que siguen es el resultado del análisis de las opiniones emitidas, pero al tratarse de la explotación de un material recogido por Internet, es decir algo que me parece bastante nuevo, me parece importante empezar por esbozar unas cuantas reflexiones en cuanto a la validez que pueda tener este material para un historiador. Me parece también interesante aludir a los métodos de trabajo elegidos y a los resultados globales antes de pasar al tema de fondo.Facultad de Humanidades y Ciencias de la Educació

    <i>Gaia</i> Data Release 1. Summary of the astrometric, photometric, and survey properties

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    Context. At about 1000 days after the launch of Gaia we present the first Gaia data release, Gaia DR1, consisting of astrometry and photometry for over 1 billion sources brighter than magnitude 20.7. Aims. A summary of Gaia DR1 is presented along with illustrations of the scientific quality of the data, followed by a discussion of the limitations due to the preliminary nature of this release. Methods. The raw data collected by Gaia during the first 14 months of the mission have been processed by the Gaia Data Processing and Analysis Consortium (DPAC) and turned into an astrometric and photometric catalogue. Results. Gaia DR1 consists of three components: a primary astrometric data set which contains the positions, parallaxes, and mean proper motions for about 2 million of the brightest stars in common with the HIPPARCOS and Tycho-2 catalogues – a realisation of the Tycho-Gaia Astrometric Solution (TGAS) – and a secondary astrometric data set containing the positions for an additional 1.1 billion sources. The second component is the photometric data set, consisting of mean G-band magnitudes for all sources. The G-band light curves and the characteristics of ∼3000 Cepheid and RR-Lyrae stars, observed at high cadence around the south ecliptic pole, form the third component. For the primary astrometric data set the typical uncertainty is about 0.3 mas for the positions and parallaxes, and about 1 mas yr−1 for the proper motions. A systematic component of ∼0.3 mas should be added to the parallax uncertainties. For the subset of ∼94 000 HIPPARCOS stars in the primary data set, the proper motions are much more precise at about 0.06 mas yr−1. For the secondary astrometric data set, the typical uncertainty of the positions is ∼10 mas. The median uncertainties on the mean G-band magnitudes range from the mmag level to ∼0.03 mag over the magnitude range 5 to 20.7. Conclusions. Gaia DR1 is an important milestone ahead of the next Gaia data release, which will feature five-parameter astrometry for all sources. Extensive validation shows that Gaia DR1 represents a major advance in the mapping of the heavens and the availability of basic stellar data that underpin observational astrophysics. Nevertheless, the very preliminary nature of this first Gaia data release does lead to a number of important limitations to the data quality which should be carefully considered before drawing conclusions from the data

    Introduction: building the history of language learning and teaching (HoLLT)

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    The papers presented in this issue are the result of a workshop held at the University of Nottingham in December 2012 as part of an Arts and Humanities Research Council research network Towards a History of Modern Foreign Language Teaching and Learning (2012–14) intended to stimulate historical research into language teaching and learning. This, the first workshop in the programme, focused on exchanging information on the history of language learning and teaching (HoLLT) across the different language traditions, for it had become clear to us that scholars working within their own language disciplines were often relatively unaware of work outside these. We hope that this special issue — with overview articles on the history of English, French, German, and Spanish as second/foreign languages — will help overcome that lack of awareness and facilitate further research collaboration. Charting the history of language teaching and learning will, in turn, make us all better informed in facing challenges and changes to policy and practice now and in the future. It is instructive in the current climate, for example, to realize that grave doubts were held about whether second foreign languages could survive alongside French in British schools in the early twentieth century (McLelland, forthcoming), or to look back at earlier attempts to establish foreign languages in primary schools (Bayley, 1989; Burstall et al., 1974; Hoy, 1977). As we write, language learning in England is undergoing yet more radical change. Language teaching for all children from the age of seven is being made compulsory in primary schools from 2014, while at Key Stage 3 (up to age 16), where a foreign language has not been compulsory since 2002, the most recent programme of study for England has virtually abandoned the recent focus on intercultural competence and now requires learners to ‘read great literature in the original language’,1 a radical change in emphasis compared to the previous half-century, which seems to reflect a very different view of what language learning is for. We seem to be little closer in 2014 than we were at the dawn of the twentieth century to answering with any certainty the questions that lie at the very foundations of language teaching: who should learn a foreign language, why learners learn, what they need to learn, and what we want to teach them — answers that we need before we can consider how we want to teach. The research programme begun under our research network is intended to help us to take ‘the long view’ on such questions

    Gaia Data Release 1: Testing parallaxes with local Cepheids and RR Lyrae stars

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    Context. Parallaxes for 331 classical Cepheids, 31 Type II Cepheids, and 364 RR Lyrae stars in common between Gaia and the Hipparcos and Tycho-2 catalogues are published in Gaia Data Release 1 (DR1) as part of the Tycho-Gaia Astrometric Solution (TGAS). Aims. In order to test these first parallax measurements of the primary standard candles of the cosmological distance ladder, which involve astrometry collected by Gaia during the initial 14 months of science operation, we compared them with literature estimates and derived new period-luminosity (PL), period-Wesenheit (PW) relations for classical and Type II Cepheids and infrared PL, PL-metallicity (PLZ), and optical luminosity-metallicity (M V -[Fe/H]) relations for the RR Lyrae stars, with zero points based on TGAS. Methods. Classical Cepheids were carefully selected in order to discard known or suspected binary systems. The final sample comprises 102 fundamental mode pulsators with periods ranging from 1.68 to 51.66 days (of which 33 with σ Ω /Ω < 0.5). The Type II Cepheids include a total of 26 W Virginis and BL Herculis stars spanning the period range from 1.16 to 30.00 days (of which only 7 with σ Ω /Ω < 0.5). The RR Lyrae stars include 200 sources with pulsation period ranging from 0.27 to 0.80 days (of which 112 with σ Ω /Ω < 0.5). The new relations were computed using multi-band (V,I,J,K s ) photometry and spectroscopic metal abundances available in the literature, and by applying three alternative approaches: (i) linear least-squares fitting of the absolute magnitudes inferred from direct transformation of the TGAS parallaxes; (ii) adopting astrometry-based luminosities; and (iii) using a Bayesian fitting approach. The last two methods work in parallax space where parallaxes are used directly, thus maintaining symmetrical errors and allowing negative parallaxes to be used. The TGAS-based PL,PW,PLZ, and M V - [Fe/H] relations are discussed by comparing the distance to the Large Magellanic Cloud provided by different types of pulsating stars and alternative fitting methods. Results. Good agreement is found from direct comparison of the parallaxes of RR Lyrae stars for which both TGAS and HST measurements are available. Similarly, very good agreement is found between the TGAS values and the parallaxes inferred from the absolute magnitudes of Cepheids and RR Lyrae stars analysed with the Baade-Wesselink method. TGAS values also compare favourably with the parallaxes inferred by theoretical model fitting of the multi-band light curves for two of the three classical Cepheids and one RR Lyrae star, which were analysed with this technique in our samples. The K-band PL relations show the significant improvement of the TGAS parallaxes for Cepheids and RR Lyrae stars with respect to the Hipparcos measurements. This is particularly true for the RR Lyrae stars for which improvement in quality and statistics is impressive. Conclusions. TGAS parallaxes bring a significant added value to the previous Hipparcos estimates. The relations presented in this paper represent the first Gaia-calibrated relations and form a work-in-progress milestone report in the wait for Gaia-only parallaxes of which a first solution will become available with Gaia Data Release 2 (DR2) in 2018. © ESO, 2017

    Gaia Early Data Release 3: Summary of the contents and survey properties

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    ABSTRACT: Context. We present the early installment of the third Gaia data release, Gaia EDR3, consisting of astrometry and photometry for 1.8 billion sources brighter than magnitude 21, complemented with the list of radial velocities from Gaia DR2. Aims. A summary of the contents of Gaia EDR3 is presented, accompanied by a discussion on the differences with respect to Gaia DR2 and an overview of the main limitations which are present in the survey. Recommendations are made on the responsible use of Gaia EDR3 results. Methods. The raw data collected with the Gaia instruments during the first 34 months of the mission have been processed by the Gaia Data Processing and Analysis Consortium and turned into this early third data release, which represents a major advance with respect to Gaia DR2 in terms of astrometric and photometric precision, accuracy, and homogeneity. Results. Gaia EDR3 contains celestial positions and the apparent brightness in G for approximately 1.8 billion sources. For 1.5 billion of those sources, parallaxes, proper motions, and the (GBP ? GRP) colour are also available. The passbands for G, GBP, and GRP are provided as part of the release. For ease of use, the 7 million radial velocities from Gaia DR2 are included in this release, after the removal of a small number of spurious values. New radial velocities will appear as part of Gaia DR3. Finally, Gaia EDR3 represents an updated materialisation of the celestial reference frame (CRF) in the optical, the Gaia-CRF3, which is based solely on extragalactic sources. The creation of the source list for Gaia EDR3 includes enhancements that make it more robust with respect to high proper motion stars, and the disturbing effects of spurious and partially resolved sources. The source list is largely the same as that for Gaia DR2, but it does feature new sources and there are some notable changes. The source list will not change for Gaia DR3. Conclusions. Gaia EDR3 represents a significant advance over Gaia DR2, with parallax precisions increased by 30 per cent, proper motion precisions increased by a factor of 2, and the systematic errors in the astrometry suppressed by 30-40% for the parallaxes and by a factor ~2.5 for the proper motions. The photometry also features increased precision, but above all much better homogeneity across colour, magnitude, and celestial position. A single passband for G, GBP, and GRP is valid over the entire magnitude and colour range, with no systematics above the 1% levelThe Gaia mission and data processing have financially been supported by ; the Spanish Ministry of Economy (MINECO/FEDER, UE) through grants ESP2016-80079-C2-1-R, ESP2016-80079-C2-2-R, RTI2018-095076-B-C21, RTI2018-095076-B-C22, BES-2016-078499, and BES-2017-083126 and the Juan de la Cierva formación 2015 grant FJCI-2015-2671, the Spanish Ministry of Education, Culture, and Sports through grant FPU16/03827, the Spanish Ministry of Science and Innovation (MICINN) through grant AYA2017-89841P for project “Estudio de las propiedades de los fósiles estelares en el entorno del Grupo Local” and through grant TIN2015-65316-P for project “Computación de Altas Prestaciones VII

    Gaia Early Data Release 3 Acceleration of the Solar System from Gaia astrometry

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    Context. Gaia Early Data Release 3 (Gaia EDR3) provides accurate astrometry for about 1.6 million compact (QSO-like) extragalactic sources, 1.2 million of which have the best-quality five-parameter astrometric solutions. Aims. The proper motions of QSO-like sources are used to reveal a systematic pattern due to the acceleration of the solar systembarycentre with respect to the rest frame of the Universe. Apart from being an important scientific result by itself, the acceleration measured in this way is a good quality indicator of the Gaia astrometric solution. Methods. Theeffect of the acceleration was obtained as a part of the general expansion of the vector field of proper motions in vector spherical harmonics (VSH). Various versions of the VSH fit and various subsets of the sources were tried and compared to get the most consistent result and a realistic estimate of its uncertainty. Additional tests with the Gaia astrometric solution were used to get a better idea of the possible systematic errors in the estimate. Results. Our best estimate of the acceleration based on Gaia EDR3 is (2.32 +/- 0.16) x 10(-10) m s(-2) (or 7.33 +/- 0.51 km s(-1) Myr-1) towards alpha = 269.1 degrees +/- 5.4 degrees, delta = -31.6 degrees +/- 4.1 degrees, corresponding to a proper motion amplitude of 5.05 +/- 0.35 mu as yr(-1). This is in good agreement with the acceleration expected from current models of the Galactic gravitational potential. We expect that future Gaia data releases will provide estimates of the acceleration with uncertainties substantially below 0.1 mu as yr(-1).Peer reviewe

    Pulsations in main sequence OBAF-type stars

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    CONTEXT: The third Gaia data release provides photometric time series covering 34 months for about 10 million stars. For many of those stars, a characterisation in Fourier space and their variability classification are also provided. This paper focuses on intermediate- to high-mass (IHM) main sequence pulsators (M ≥  1.3 M⊙) of spectral types O, B, A, or F, known as β Cep, slowly pulsating B (SPB), δ Sct, and γ Dor stars. These stars are often multi-periodic and display low amplitudes, making them challenging targets to analyse with sparse time series. AIMS: We investigate the extent to which the sparse Gaia DR3 data can be used to detect OBAF-type pulsators and discriminate them from other types of variables. We aim to probe the empirical instability strips and compare them with theoretical predictions. The most populated variability class is that of the δ Sct variables. For these stars, we aim to confirm their empirical period-luminosity (PL) relation, and verify the relation between their oscillation amplitude and rotation. METHODS: All datasets used in this analysis are part of the Gaia DR3 data release. The photometric time series were used to perform a Fourier analysis, while the global astrophysical parameters necessary for the empirical instability strips were taken from the Gaia DR3 gspphot tables, and the v sin i data were taken from the Gaia DR3 esphs tables. The δ Sct PL relation was derived using the same photometric parallax method as the one recently used to establish the PL relation for classical Cepheids using Gaia data. RESULTS: We show that for nearby OBAF-type pulsators, the Gaia DR3 data are precise and accurate enough to pinpoint them in the Hertzsprung-Russell (HR) diagram. We find empirical instability strips covering broader regions than theoretically predicted. In particular, our study reveals the presence of fast rotating gravity-mode pulsators outside the strips, as well as the co-existence of rotationally modulated variables inside the strips as reported before in the literature. We derive an extensive period–luminosity relation for δ Sct stars and provide evidence that the relation features different regimes depending on the oscillation period. We demonstrate how stellar rotation attenuates the amplitude of the dominant oscillation mode of δ Sct stars. CONCLUSIONS: The Gaia DR3 time-series photometry already allows for the detection of the dominant (non-)radial oscillation mode in about 100 000 intermediate- and high-mass dwarfs across the entire sky. This detection capability will increase as the time series becomes longer, allowing the additional delivery of frequencies and amplitudes of secondary pulsation modes
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