29 research outputs found

    Unveiling the nature of the "Green Pea" galaxies

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    We review recent results on the oxygen and nitrogen chemical abundances in extremely compact, low-mass starburst galaxies at redshifts between 0.1-0.3 recently named to as "Green Pea" galaxies. These galaxies are genuine metal-poor galaxies (\sim one fifth solar) with N/O ratios unusually high for galaxies of the same metallicity. In combination with their known general properties, i.e., size, stellar mass and star-formation rate, these findings suggest that these objects could be experiencing a short and extreme phase in their evolution. The possible action of both recent and massive inflow of gas, as well as stellar feedback mechanisms are discussed here as main drivers of the starburst activity and their oxygen and nitrogen abundances.Comment: To appear in JENAM Symposium "Dwarf Galaxies: Keys to Galaxy Formation and Evolution", P. Papaderos, G. Hensler, S. Recchi (eds.). Lisbon, September 2010, Springer Verlag, in pres

    The interplay between ionized gas and massive stars in the HII galaxy IIZw70: integral field spectroscopy with PMAS

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    We performed an integral field spectroscopic study for the HII galaxy IIZw70 in order to investigate the interplay between its ionized interstellar medium (ISM) and the massive star formation (SF). Observations were taken in the optical spectral range (3700-6800 A) with the Potsdam Multi-Aperture Spectrophotometer (PMAS) attached to the 3.5 m telescope at CAHA. We created and analysed maps of spatially distributed emission-lines, continuum emission and properties of the ionized ISM (e.g. physical-chemical conditions, dust extinction, kinematics). We investigated the relation of these properties to the spatial distribution and evolutionary stage of the massive stars. For the first time we have detected the presence of Wolf-Rayet (WR) stars in this galaxy. The peak of the ionized gas emission coincides with the location of the WR bump. The region of the galaxy with lower dust extinction corresponds to the region that shows the lowest values of velocity dispersion and radial velocity. The overall picture suggests that the ISM of this region is being disrupted via photoionization and stellar winds, leading to a spatial decoupling between gas+stars and dust clouds. The bulk of dust appears to be located at the boundaries of the region occupied by the probable ionizing cluster. We also found that this region is associated to the nebular emission in HeII4686 and to the intensity maximum of most emission lines. This indicates that the hard ionizing radiation responsible for the HeII4686 nebular emission can be related to the youngest stars. Within \sim 0.4 x 0.3 kpc^2 in the central burst, we derived O/H using direct determinations of Te[OIII]. We found abundances in the range 12+log(O/H)=7.65-8.05, yielding an error-weighted mean of 12+log(O/H)=7.86 ±\pm0.05.Comment: 10 pages, 10 figures, accepted for publication in A&A, minor changes adde

    MEGARA, the new intermediate-resolution optical IFU and MOS for GTC: getting ready for the telescope

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    MEGARA (Multi-Espectrógrafo en GTC de Alta Resolución para Astronomía) is an optical Integral-Field Unit (IFU) and Multi-Object Spectrograph (MOS) designed for the GTC 10.4m telescope in La Palma that is being built by a Consortium led by UCM (Spain) that also includes INAOE (Mexico), IAA-CSIC (Spain), and UPM (Spain). The instrument is currently finishing AIV and will be sent to GTC on November 2016 for its on-sky commissioning on April 2017. The MEGARA IFU fiber bundle (LCB) covers 12.5x11.3 arcsec2 with a spaxel size of 0.62 arcsec while the MEGARA MOS mode allows observing up to 92 objects in a region of 3.5x3.5 arcmin2 around the IFU. The IFU and MOS modes of MEGARA will provide identical intermediate-to-high spectral resolutions (RFWHM~6,000, 12,000 and 18,700, respectively for the low-, mid- and high-resolution Volume Phase Holographic gratings) in the range 3700-9800ÅÅ. An x-y mechanism placed at the pseudo-slit position allows (1) exchanging between the two observing modes and (2) focusing the spectrograph for each VPH setup. The spectrograph is a collimator-camera system that has a total of 11 VPHs simultaneously available (out of the 18 VPHs designed and being built) that are placed in the pupil by means of a wheel and an insertion mechanism. The custom-made cryostat hosts a 4kx4k 15-μm CCD. The unique characteristics of MEGARA in terms of throughput and versatility and the unsurpassed collecting are of GTC make of this instrument the most efficient tool to date to analyze astrophysical objects at intermediate spectral resolutions. In these proceedings we present a summary of the instrument characteristics and the results from the AIV phase. All subsystems have been successfully integrated and the system-level AIV phase is progressing as expected

    How to move ionized gas: an introduction to the dynamics of HII regions

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    This review covers the dynamic processes that are important in the evolution and structure of galactic HII regions, concentrating on an elementary presentation of the physical concepts and recent numerical simulations of HII region evolution in a non-uniform medium. The contents are as follows: (1) The equations (Euler equations; Radiative transfer; Rate equations; How to avoid the dynamics; How to avoid the atomic physics). (2) Physical concepts (Static photoionization equilibrium; Ionization front propagation; Structure of a D-type front; Photoablation flows; Other ingredients - Stellar winds, Radiation pressure, Magnetic fields, Instabilities). (3) HII region evolution (Early phases: hypercompact and ultracompact regions; Later phases: compact and extended regions; Clumps and turbulence).Comment: To be published as a chapter in 'Diffuse Matter from Star Forming Regions to Active Galaxies' - A volume Honouring John Dyson. Eds. T. W. Harquist, J. M. Pittard and S. A. E. G. Falle. 25 pages, 7 figures. Some figures degraded to meet size restriction. Full-resolution version available at http://www.ifront.org/wiki/Dyson_Festschrift_Chapte

    Uncovering multiple Wolf-Rayet star clusters and the ionized ISM in Mrk 178: the closest metal-poor Wolf-Rayet H ii galaxy

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    New integral field spectroscopy (IFS) has been obtained for the nearby metal-poor Wolf–Rayet (WR) galaxy Mrk 178 to examine the spatial correlation between its WR stars and the neighbouring ionized interstellar medium (ISM). The strength of the broad WR features and its low metallicity make Mrk 178 an intriguing object. We have detected the blue and red WR bumps in different locations across the field of view (∼300 pc × 230 pc) in Mrk 178. The study of the WR content has been extended, for the first time, beyond its brightest star-forming knot uncovering new WR star clusters. Using Large/Small Magellanic Cloud-template WR stars, we empirically estimate a minimum of ∼20 WR stars within the region sampled. Maps of the spatial distribution of the emission lines and of the physical–chemical properties of the ionized ISM have been created and analysed. Here, we refine the statistical methodology by Pérez-Montero et al. (2011) to probe the presence of variations in the ISM properties. An error-weighted mean of 12+log(O/H) = 7.72 ± 0.01 is taken as the representative oxygen abundance for Mrk 178. A localized N and He enrichment, spatially correlated with WR stars, is suggested by this analysis. Nebular He II λ4686 emission is shown to be spatially extended reaching well beyond the location of the WR stars. This spatial offset between WRs and He II emission can be explained based on the mechanical energy input into the ISM by the WR star winds, and does not rule out WR stars as the He II ionization source. We study systematic aperture effects on the detection and measurement of the WR features, using Sloan Digital Sky Survey spectra combined with the power of IFS. In this regard, the importance of targeting low metallicity nearby systems is discussed

    Derecho ex cathedra. 1847-1936 Diccionario de catedráticos españoles

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    Edición revisada 2020.Publicación de las entradas biográficas del Diccionario de catedráticos españoles de Derecho, accesible en http://www.uc3m.es/diccionariodecatedraticos. Al dar forma de libro al material hemos prescindido de algunos elementos informativos, que se mantienen en la página electrónica indicada. Se recogen ahora solamente a los ingresados en el cuerpo con anterioridad a la guerra civil.Publication of the biographical entries of the Diccionario de catedráticos españoles de Derecho, accessible at http://www.uc3m.es/diccionariodecatedraticos. By giving those material book form, we have dispensed with some informative elements, however kept on the web page. Only professors apointed prior to the Civil War are now included.Esta publicación forma parte del proyecto “La memoria del jurista español: génesis y desarrollo de las disciplinas jurídicas” (ref. DER2014-55035-C2-1-P/DER2014-55035-C2-2-P), financiado por el Ministerio de Economía, Industria y Competitividad (España)

    Radiopharmacological research of a new renal imaging agent

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    99mTc(I)hexaquis(carboximetilisonitrilo), 99mTc-CAMI, obtenido con P.RQ. > 95%, se evaluó en diferentes modelos experimentales. Estudios de biodistribución en ratón mostraron alta y rápida depuración renal (>80% a 20 min), similar al 99mTc-MAG3, radiofármaco rutinario actual. Autorradiografías de riñon de ratas no evidenciaron captación preferencial del compuesto por las estructuras renales médula o corteza, confirmándose el rápido tránsito renal. Estudios centellográficos en perros normales (n = S), mostraron que la curva renográfica se aproxima morfológicamente a la obtenida con 99mTc-MAG3, con parámetros cuantitativos comparables. Las imágenes seriocentellográficas indican menor acumulación hepática con mejor definición de las imágenes renales y ureterales. Análisis de muestras de orina de perros inyectados con el complejo no evidencia metabolización del producto. Las investigaciones realizadas permiten inferir que el 99mTc-CAMI exhibe apropiadas propiedades biológicas como agente diagnóstico de funcionalidad renal.99mTc(I) hexakis(carboxymethylisocyanide), 99mTc-CAMI, obtained with R.Q.P.> 95%, was studied in experimental models. Mice biodistribution showed high and rapidly renal cleareance (> 80% at 20 min) similar to the comercial renal agent 99mTc-MAG3 Rat kidney autoradiography confirm these behaviour and demonstrated no significative differences in renal structure radioactivity uptake levels. Scintigraphic studies in normal dogs (n = 5) showed that the new product yields a renographic curve similar to that of 99mTc-MAG3. Cuantitative analysis of renographic parameters confirm the similar behaviour of the two compounds. The scintigraphic images of 99mTc-CAMI show less hepatic uptake compared with 99mTc- MAG3 so a better definitioh of the kidneys and ureters is possible. No signs of metabolization were observed in RP-HPLC urine analysis. These data show that 99mTc-CAMI exhibits appropiate biological properties for a renal function imaging agerit.Colegio de Farmacéuticos de la Provincia de Buenos Aire

    Hubble constant and nuclear equation of state from kilonova spectro-photometric light curves

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    The merger of two compact objects of which at least one is a neutron star is signalled by transient electromagnetic emission in a kilonova (KN). This event is accompanied by gravitational waves and possibly other radiation messengers such as neutrinos or cosmic rays. The electromagnetic emission arises from the radioactive decay of heavy r-process elements synthesized in the material ejected during and after the merger. In this paper we show that the analysis of KNe light curves can provide cosmological distance measurements and constrain the properties of the ejecta. In this respect, MAAT, the new Integral Field Unit in the OSIRIS spectrograph on the 10.4 m Gran Telescopio CANARIAS (GTC), is well suited for the study of KNe by performing absolute spectro-photometry over the entire 3600 − 10 000 Å spectral range. Here, we study the most representative cases regarding the scientific interest of KNe from binary neutron stars, and we evaluate the observational prospects and performance of MAAT on the GTC to do the following: (a) study the impact of the equation of state on the KN light curve, and determine to what extent bounds on neutron star (NS) radii or compactness deriving from KN peak magnitudes can be identified and (b) measure the Hubble constant, H0, with precision improved by up to 40%, when both gravitational wave data and photometric-light curves are used. In this context we discuss how the equation of state, the viewing angle, and the distance affect the precision and estimated value of H0

    . 61 (2005) mayo-agosto. Historias. Revista de la Dirección de Estudios Históricos

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    - La historia de la Exposición de la Armería por Walt Kuhn. - Las ideas sobre la felicidad en Rusia, siglos XVII-XVIII por O. E. Kosheleva. - El ejemplo como categoría política por Javier Gomá Lanzón. - Los límites de “lo público”. Conflictos por el uso del caudal del río Magdalena en el valle de México durante el Porfiriato por Mario Barbosa Cruz. - La correspondencia de Joaquín García Icazbalceta con Manuel Remón Zarco del Valle por Rodrigo Martínez Baracs. - La geografía como disciplina científica. Por un reencuentro con la historia por Eulalia Ribera Carbó. - “Indígenas, mezclados y blancos”, según el Censo General de Habitantes de 1921 por Dolores Pla Brugat. - Holger Cahill y el inje-inje. La historia del primitivismo modernista por Alan Moore. - Despotismo virreinal en el siglo XVIII: Bando del marqués de Croix del 8 de diciembre de 1769 por Esteban Sánchez de Tagle. - José Justo Gómez de la Cortina: el personaje, el escritor y el periodista por Mariana Riva Palacio Quintero. - Tlalocan purépecha por Rodrigo Martínez Baracs. - Melancólicos y endemoniados en Nueva España por Antonio Rubial García. - González Obregón revisitado por Marcela Dávalos. – Crestomanía por José Mariano Leyva
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