Formación del profesorado en pedagogía intercultural: contenidos actitudinales

La inmigración es una realidad en las sociedades occidentales; una situación que, aunque no es nueva, sí se manifiesta con dimensiones no conocidas hasta ahora en nuestro país, no sólo por su incremento cuantitativo sino por la variabilidad detectada. Necesariamente esta nueva situación afecta o puede afectar a la cohesión social. El problema es multidimensional y sólo desde diferentes marcos coordinados podremos ofrecer una “hospitalidad” por parte de nuestra cultura mayoritaria, que no genere problemas de convivencia y facilite la intercomunicación enriquecedora para todos, basada en el respeto. Para afrontar esta nueva situación no basta con el entusiasmo voluntario del profesorado si no se acompaña de apoyos institucionales y sociales, y por supuesto, de fondos económicos. Sin embargo, tampoco es suficiente manifestar una actitud positiva hacia el multiculturalismo, sin racionalizar y sistematizar el trabajo a realizar

A search for new hot subdwarf stars by means of Virtual Observatory tools

Hot subdwarf stars are faint, blue objects, and are the main contributors to the far-UV excess observed in elliptical galaxies. They offer an excellent laboratory to study close and wide binary systems, and to scrutinize their interiors through asteroseismology, as some of them undergo stellar oscillations. However, their origins are still uncertain, and increasing the number of detections is crucial to undertake statistical studies. In this work, we aim at defining a strategy to find new, uncatalogued hot subdwarfs. Making use of Virtual Observatory tools we thoroughly search stellar catalogues to retrieve multi-colour photometry and astrometric information of a known sample of blue objects, including hot subdwarfs, white dwarfs, cataclysmic variables and main sequence OB stars. We define a procedure to discriminate among these spectral classes, particularly designed to obtain a hot subdwarf sample with a low contamination factor. In order to check the validity of the method, this procedure is then applied to two test sky regions: the Kepler FoV and to a test region of around (RA:225, DEC:5) deg. As a result, we obtained 38 hot subdwarf candidates, 23 of which had already a spectral classification. We have acquired spectroscopy for three other targets, and four additional ones have an available SDSS spectrum, which we used to determine their spectral type. A temperature estimate is provided for the candidates based on their spectral energy distribution, considering two-atmospheres fit for objects with clear infrared excess. Eventually, out of 30 candidates with spectral classification, 26 objects were confirmed to be hot subdwarfs, yielding a contamination factor of only 13%. The high rate of success demonstrates the validity of the proposed strategy to find new uncatalogued hot subdwarfs. An application of this method to the entire sky will be presented in a forthcoming work.Comment: 13 pages, 7 figure

Deep into the Water Fountains: The case of IRAS 18043-2116

(Abridged) The formation of large-scale (hundreds to few thousands of AU) bipolar structures in the circumstellar envelopes (CSEs) of post-Asymptotic Giant Branch (post-AGB) stars is poorly understood. The shape of these structures, traced by emission from fast molecular outflows, suggests that the dynamics at the innermost regions of these CSEs does not depend only on the energy of the radiation field of the central star. Deep into the Water Fountains is an observational project based on the results of programs carried out with three telescope facilities: The Karl G. Jansky Very Large Array (JVLA), The Australia Telescope Compact Array (ATCA), and the Very Large Telescope (SINFONI-VLT). Here we report the results of the observations towards the WF nebula IRAS 18043$-$2116: Detection of radio continuum emission in the frequency range 1.5GHz - 8.0GHz; H$_{2}$O maser spectral features and radio continuum emission detected at 22GHz, and H$_{2}$ ro-vibrational emission lines detected at the near infrared. The high-velocity H$_{2}$O maser spectral features, and the shock-excited H$_{2}$ emission detected could be produced in molecular layers which are swept up as a consequence of the propagation of a jet-driven wind. Using the derived H$_{2}$ column density, we estimated a molecular mass-loss rate of the order of $10^{-9}$M$_{\odot}$yr$^{-1}$. On the other hand, if the radio continuum flux detected is generated as a consequence of the propagation of a thermal radio jet, the mass-loss rate associated to the outflowing ionized material is of the order of 10$^{-5}$M$_{\odot}$yr$^{-1}$. The presence of a rotating disk could be a plausible explanation for the mass-loss rates estimated.Comment: 10 pages, 5 figures. Accepted for publication in A&

Modelización geoquímica de los procesos de fusión parcial

18 páginas, 6 figuras, 1 apendice.[ES] Durante la fusión, los elementos traza y los isótopos estables sufren fraccionación mientras que los isótopos radiogénicos no varían. Como la distribución de los primeros entre las fases que intervienen sigue las leyes de las soluciones diluidas, se pueden establecer ecuaciones relativamente sencillas, que posibilitan la modelización del proceso. A su vez, el comportamiento de los isótopos radiogénicos hace que los magmas hereden la signatura del sólido del que derivar, lo que facilita la identificación del mismo. Las ecuaciones propuestas para los diferentes tipos de fusión indican que en la fusión en equilibrio la abundancia en el fundido de elementos traza altamente incompatibles alcanza valores muy elevados al comienzo del proceso y disminuye progresivamente al aumentar el grado de fusión, mientras que la concentración de los elementos compatibles crece lentamente al aumentar el porcentaje de fusión y bruscamente cuando éste alcanza valores muy altos. En la fusión fraccionada el primero de los líquidos que se genera removiliza casi completamente a todos los elementos altamente incompatibles del sistema, y los sucesivos líquidos producidos tienen muy baja concentración en dichos elementos. En la fusión incongruente se generan líquidos ricos en aquellos elementos traza que tienen altos coeficientes de reparto para las fases que funden y bajos para las de nueva formación, mientras que están empobrecidos en los elementos que entran en estas últimas fases. Si la fusión tiene lugar en presencia de una fase fluida el líquido está empobrecido, en relación al generado cuando dicha fase está ausente, en aquellos elementos que tienen coeficientes de reparto líquido-fluido aproximadamente iguales a la unidad, ya que una parte de los mismos se concentra en el fluido. Finalmente, en la fusión en desequilibrio o no difusión a la primera fracción de líquido que aparece tiene una concentración en elementos incompatibles superior y en elementos compatibles inferior a la del sólido del que deriva, con lo que la interfase sólido-líquido se empobrece y se enriquece, respectivamente. Sin embargo, al final del proceso la concentración de los elementos en el líquido se iguala a la que tenía la parte de sólido que ha fundido. Para modelizar la fusión parcid en equilibrio se pueden seguir dos vías diferentes, según se disponga o no de los coefcientes de reparto mineral-líquido y se conozcan o no los porcentajes en los que intervienen dichas fases. Si se dispone de dichos parámetros, se puede intentar duplicar las concentraciones elementales observadas en los líquidos primarios, previa selección de unas constantes razonables. Por el contrario, si no se conocen aquellos parámetros la mJdelización se puede llevar a cabo de forma distinta, según se disponga de la composición de los líquidos generados o del residuo. Si se conoce la composición de los líquidos generados, se utilizan las variaciones en las concentraciones elementales que presentan las rocas, mediante un ajuste simultáneo de todas ellas por resolución de un sistema de ecuaciones formado por las expresiones que describen el proceso, para un número suficiente de elementos, o bien independientemente para cada parámetro y elemento. A su vez, si se conoce la composición química de los residuos hay que suponer la composición del protolito y a partir del elemento más residual fijar los dos parámetros que quedan por conocer: el coeficiente de partición global residuofundido para los distintos elementos y el grado de fusión que ha sufrido cada restita, asumiendo, según proceda, el grado de fusión, el coeficiente de reparto global de uno de los elementos o la concentración del mismo.[EN] During melting processes both stable isotopes and trace elements fractionate, whereas radiogenic isotopes do not change. The distribution of the former between the phases that participate, follows diluted solutions laws in such a way that it is possible to establish relatively simple equations to model these processes. Additionally, the radiogenic isotopes behaviour implies that the magmas retain the source signature thus allowing its identification. In the case of equilibrium melting, the highly incompatible elements abundance is very high in the liquid at the beginning of the process and decreases progressively as the melting degree increases. On the contrary, the concentration in compatible elements grows very slowly during the first steps to increase sharply for the highest F values. During fractional melting, the first liquid generated removes almost all the incompatible elements thus producing a relative depletion in those elements in the successive liquids. In the case of incongruent melting, the magmas are enriched in the trace elements with high distribution coefficients for the phases that melt and low for the newly generated phases, and are impoverished in the elements that constitute the new phases. If melting is produced in the presence of a fluid phase, the liquid will be depleted in those elements with fluid/liquid distribution coefficients close to 1, rdative to the same liquid generated without a fluid phase. Finally, during disequilibrium or nondiffusive melting, the first liquid fraction has a concentration in incompatible dements higher and in compatible elements lower than that in the source, so the solid-liquid interface is depleted and enriched, respectively. However, at the end of the process the concentration of elements in the liquid is equated to the abundance in the solid that melted. To model equilibrium me1ting two diferent approaches can be followed, depending on the availability of the mineral-liquid distribution coefficients and the percentages in which the mineral phases have participated. When these parameters are known, it is possible to duplicate the concentrations observed in the primary liquids by selecting reasonable constants. On the contrary, when these parameters are unknown the approach to follow will depend on the knowledge of the cbmposition of the liquids or that of the residue. In the first case, the element concentrations of tbe rocks are used to obtain a simultaneous best-fit solution of a system constituted by tile equations that describe the process, either for a number of elements, or individually for each parameter and element. If the composition of the residue is known, it is necessary to guess the composition of the protolith. Then, from the most residual element the two remaining parameters (the residue- melt bulk distribution coefficient and the degree of melting of each restite) are defined, either assuming the degree of melting, the elements bulk distribution coefficient, or their concentration.Este trabajo se ha realizado dentro del Proyecto de Investigación PB92-lOS «Magmatismo intraplaca relacionado con puntos calientes en la Península Ibérica», financiado por la Dirección General de Investigación Científica y Técnica.Peer reviewe

Integral Field Spectroscopy Of The Brightest Knots Of Hh 223 In L723

HH 223 is the optical counterpart of a larger scale H2 outflow, driven by the protostellar source VLA 2A, in L723. Its poorly collimated and rather chaotic morphology suggested the Integral Field Spectroscopy (IFS) as an appropriate option to map the emission for deriving the physical conditions and the kinematics. Here we present new results based on the IFS observations made with the INTEGRAL system at the WHT. The brightest knots of HH 223 (\sim16 arcsec, 0.02 pc at a distance of 300 pc) were mapped with a single pointing in the spectral range 6200-7700 A. We obtained the emission-line intensity maps for Halpha, [NII] 6584 A and [SII] 6716, 6731 A, and explored the distribution of the excitation and electron density from [NII]/Halpha, [SII]/Halpha, and [SII] 6716/6731 line-ratio maps. Maps of the radial velocity field were obtained. We analysed the 3D-kinematics by combining the knot radial velocities, derived from IFS data, with the knot proper motions derived from multi-epoch, narrow-band images. The intensity maps built from IFS data reproduced well the morphology found in the narrow-band images. We checked the results obtained from previous long-slit observations with those derived from IFS spectra extracted with a similar spatial sampling. At the positions intersected by the slit, the physical conditions and kinematics derived from IFS are compatible with those derived from long-slit data. In contrast, significant discrepancies were found when the results from long-slit data were compared with the ones derived from IFS spectra extracted at positions shifted a few arcsec from those intersected by the slit. This clearly revealed IFS observations as the best choice to get a reliable picture of the HH emission properties.Comment: 9 pages, 8 figures; Accepted for MNRA