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Nomenclatura Unesco > (21) Astronomía y Astrofísica

Mostrando recursos 61 - 80 de 380

61. Supernovae and dark energy - Domínguez, Inmaculada; Bravo Guil, Eduardo; Piersanti, Luciano; Straniero, Oscar; Tornambé, Amedeo
A decade ago the observations of thermonuclear supernovae at high-redhifts showed that the expansion rate of the Universe is accelerating and since then, the evidence for cosmic acceleration has gotten stronger. This acceleration requires that the Universe is dominated by dark energy, an exotic component characterized by its negative pressure. Nowadays all the available astronomical data (i.e. thermonuclear supernovae, cosmic microwave background, barionic acoustic oscillations, large scale structure, etc.) agree that our Universe is made of about 70% of dark energy, 25% of cold dark matter and only 5% of known, familiar matter. This Universe is geometrically flat, older than previously...

62. A population synthesis study of the luminosity function of hot white dwarfs - Torres Gil, Santiago; García-Berro Montilla, Enrique; Krzesinski, Jurek; Kleinman, Scot J.
Context. We present a coherent and detailed Monte Carlo simulation of the population of hot white dwarfs. We assess the statistical significance of the hot end of the white dwarf luminosity function and the role played by the bolometric corrections of hydrogen-rich white dwarfs at high effective temperatures. Aims. We use the most up-to-date stellar evolutionary models and implement a full description of the observational selection biases to obtain realistic simulations of the observed white dwarf population. Methods. Our theoretical results are compared with the luminosity function of hot white dwarfs obtained from the Sloan Digital Sky Survey (SDSS), for...

63. Observation of SN2011fe with INTEGRAL - I : pre-maximum phase - Isern Vilaboy, Jordi; Jean, Pierre; Bravo Guil, Eduardo; Diehl, Roland; Knödlseder, Jurgen; Domingo, A.; Hirschmann, Alina; Hoeflich, Peter; Lebrun, F.; Renaud, M.; Soldi, Simona; Elias-Rosa, Nancy; Hernanz Carbó, Margarita; Kulebi, Baybar; Zhang, X.; Badenes Montoliu, Carles; Domínguez, Inmaculada; García Senz, Domingo; Jordi, Carme; Lichti, G.; Vedrenne, G.; von Ballmoos, Peter
Context. SN2011fe was detected by the Palomar Transient Factory in M101 on August 24, 2011, a few hours after the explosion. From the early optical spectra it was immediately realized that it was a Type Ia supernova, thus making this event the brightest one discovered in the past twenty years. Aims. The distance of the event offered the rare opportunity of performing a detailed observation with the instruments onboard INTEGRAL to detect the ¿-ray emission expected from the decay chains of 56Ni. The observations were performed in two runs, one before and around the optical maximum, aimed to detect the early...

64. A Super-solar metallicity for the progenitor of Kepler's supernova - Park, Sangwook; Badenes Montoliu, Carles; Mori, Koji; Kaida, Ryohei; Bravo Guil, Eduardo; Schenck, Andrew; Eriksen, Kristoffer A.; Hughes, John P.; Slane, Patrick O.; Burrows, David N.; Lee, Jae-Joon
We have performed deep X-ray observations of the remnant of Kepler's supernova (SN 1604) as a Key Project of the Suzaku Observatory. Our main goal is to detect secondary Fe-peak elements in the supernova (SN) ejecta to gain insights into the Type Ia SN explosion mechanism and the nature of the progenitor. Here, we report our initial results. We made a conclusive detection of X-ray emission lines from highly ionized Mn, Cr, and Ni as well as Fe. The observed Mn-to-Cr line flux ratio is ~0.60, ~30% larger than that measured in Tycho's remnant. We estimate an Mn-to-Cr mass ratio...

65. Experiments on the Ionospheric Models in GNSS - Vinh, La The; Quang, Phuong Xuan; García Rigo, Alberto; Rovira Garcia, Adrià; Ibáñez Segura, Marcos - Deimos
In GNSS, one of the main error sources of the Standard Positioning Service (SPS) is introduced by the ionosphere. Although this error can be cancelled by combining two signals at different frequencies, most of the single - frequency mass - market receivers do not benefit from this cancel l ation. For that reason, a set of parameter s is included in the navigation message in order to compute the ionospheric delay of any observation by the Klobuchar model. The Klobuchar model is a very simple model that is able to remove more than the 50% of the ionospheric delay. Recently, more accurate ionospheric models have been introduced such as Global Ionospheric Map (GIM) or the F ast P recise P oint P ositioning ( F PPP ) ionospheric model. In...

66. Testando as Propriedades Físicas do Modelo Unificado de Galáxias de Núcleo Ativo - Audibert, Anelise

67. A galáxia NGC 7020: estudo de populações estelares e de órbitas especiais na sua barra - Bueno, Felipe Augusto Bianchi

68. Perfis de Densidade de Matéria na Redondeza Solar - Aguiar, Gabriel Corrêa de

69. Algoritmo para extração fotométrica nos dados do ESO-VVV: o aglomerado estelar massivo Pismis 24 - Dias, Rafael Augusto Garcia

70. Determinação do campo magnético de estrelas anãs brancas através do efeito Zeeman quadrático - Wilsmann, Karin Wittmann

71. Caracterização das cordas cósmicas girantes a partir da modelagem pela teoria de gravitação de Brans-Dicke - Silva, Renan Floriano da

72. Classificação Espectral de Anãs Brancas - Ourique, Gustavo

73. Mached Filter na Detecção de Caudas de Maré - Queiroz, Anna Barbara de Andrade

74. Revista Mexicana de Astronomía y Astrofísica : Universidad Nacional Autónoma de México. Instituto de Astronomía

75. Mathematical Methods Applied to the Celestial Mechanics of Artificial Satellites 2013 - Prado, Antonio F. Bertachini A.; Masdemont Soler, Josep; Zanardi, Maria Cecilia; Winter, Silvia Maria Giuliatti; Yokoyama, Tadashi; Gomes, Vivian Martins
Postprint (published version)

76. Lagrange y la primera formulación de la mecánica analítica - Navarro, Luis

77. Solar EUV flux rate estimation during mid and strong flares from the ionospheric electron content response signature in GNSS observations - Hernández Pajares, Manuel; García Rigo, Alberto; Juan Zornoza, José Miguel; Sanz Subirana, Jaume; Monte Moreno, Enrique; Aragón Ángel, María Ángeles
A simple and precise technique to measure the sudden Extreme Ultraviolet (EUV) radiation increase of the Sun, during mid and strong flares, has been formulated and demonstrated for the most active part of the last Solar Cycle. On the one hand, it is based on the short time scale of these events, which allows the validity of a simple global overionization model. And on the other hand on the prompt ionospheric response to the EUV ionization, which signature (in terms of the Global Navigation Satellite Systems -GNSSSolar Flare Activity Indicator, GSFLAI) is accurately measured in real-time from the existing global...

78. Impact of higher order ionospheric delay on precise GNSS computation - Hernández Pajares, Manuel; Aragón Ángel, María Ángeles; Defraigne, Pascale; Bergeot, Nicolas; Prieto Cerdeira, Roberto; Sanz Subirana, Jaume
Peer Reviewed

79. The shape of a galaxy is not much influenced by the potential as it might seem - Cubarsí Morera, Rafael
The dynamics of a galaxy as a stellar system in statistical equilibrium is usually obtained from the superposition principle, based on the linearity of the Boltzmann collisionless equation (BCE) in regard to the phase space density function. The term statistical equilibrium is a notion coming from statistical dynamics, although, from an analytical dynamics viewpoint, it should be associated with an invariant (conservative) density function under the BCE in the phase space. Similarly, dissipative forces like dynamical friction, which are essential to statistical dynamics, emerge in analytical dynamics via non steady-state phase density functions and/or potentials as solutions of the BCE....

80. UV to far-IR reflectance spectra of carbonaceous chondrites - I. Implications for remote characterization of dark primitive asteroids targeted by sample-return missions - Trigo Rodríguez, Josep Maria; Moyano Cambero, Carles E.; Llorca Piqué, Jordi; Fornasier, Sonia; Barucci, Maria Antonietta; Belskaya, Irina N.; Martins, Zita; Rivkin, Andrew S.; Dotto, Elisabetta; Madiedo, José María; Alonso Azcárate, Jacinto
We analyse here a wide sample of carbonaceous chondrites from historic falls (e.g. Allende, Cold Bokkeveld, Kainsaz, Leoville, Murchison, Murray, Orgueil and Tagish Lake) and from NASA Antarctic collection.With the analysis of these meteorites we want to get new clues on the role of aqueous alteration in promoting the reflectance spectra diversity evidenced in the most primitive chondrite groups. The selected meteorite specimens are a sample large enough to exemplify how laboratory reflectance spectra of rare groups of carbonaceous chondrites exhibit distinctive features that can be used to remotely characterize the spectra of primitive asteroids. Our spectra cover the full electromagnetic spectrum from 0.2 to 25 μm...

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