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Hemispheric distributions and interannual variability of NOy produced by energetic particle precipitation in 2002-2012

Titulo: 
Hemispheric distributions and interannual variability of NOy produced by energetic particle precipitation in 2002-2012
Autores: 
Funke, B; Lopez-Puertas, M; Holt, L; Randall, CE; Stiller, GP; von Clarmann, T
Resumen: 
We investigate the interannual variability and hemispheric differences of reactive odd nitrogen produced by energetic particle precipitation (EPP-NOy) and transported into the stratosphere and lower mesosphere during polar winters in 2002-2012. For this purpose, EPP-NOy amounts derived from observations of the Michelson Interferometer for Passive Atmospheric Sounding by means of a tracer correlation method have been used. Southern hemispheric (SH) seasonal maximum EPP-NOy amounts transported below the 0.02 hPa level range from 0.5GM to 2.5GM in the 2009 and 2003 winters, respectively. Northern hemispheric (NH) amounts were typically 2-5 times smaller, with the exception of the 2003/2004 winter. This interhemispheric asymmetry is primarily caused by a reduction of the mesospheric descent rates in NH midwinter, as opposed to the SH. Hemispherically integrated NOy fluxes through given pressure levels reach up to 0.07 GM/day at 0.1 hPa. A multilinear regression of the EPP-NOy evolution to the A(p) index of the preceding months indicates that a large fraction of the SH interannual variability of EPP-NOy (excluding direct contributions by solar protons) can be linked to geomagnetic activity variations. This relationship holds throughout the winter and at all vertical levels where EPP-NOy is present. In the NH, a similar correlation is found until midwinter, however, breaking down afterward above 2 hPa in years with elevated stratopause occurrence. As an exception, EPP-NOy amounts in the Arctic winter 2004/2005 were much higher than in other NH winters with similar geomagnetic activity. We attribute this behavior to the unusually stable polar vortex in that winter, otherwise typical for the SH.
Autor principal: 
Funke, B
Autor/es del IAA: 
Funke, B.; Lopez-Puertas, M.
DOI: 
10.1002/2014JD022423
Revista: 
JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES
Fecha de publicación: 
2014/12/16
Volumen: 
119
Issue: 
23
Páginas: 
13565-13582
Tipo de documento: 
Article

Mutiny at the white-hole district

Titulo: 
Mutiny at the white-hole district
Autores: 
Barcelo, C; Carballo-Rubio, R; Garay, LJ
Resumen: 
The white-hole sector of Kruskal's solution is almost never used in physical applications. However, it might contain the solution to many of the problems associated with gravitational collapse and evaporation. This paper tries to draw attention to some bouncing geometries that make a democratic use of the black- and white-hole sectors. We will argue that these types of behavior could be perfectly natural in some approaches to the next physical level beyond classical general relativity.
Autor principal: 
Barcelo, C
Autor/es del IAA: 
Barcelo, Carlos; Carballo-Rubio, Raul
DOI: 
10.1142/S021827181442022X
Revista: 
INTERNATIONAL JOURNAL OF MODERN PHYSICS D
Fecha de publicación: 
2014/10
Volumen: 
23
Issue: 
12
Tipo de documento: 
Article
Palabras clave: 
Black holes; white holes; gravitational collapse
Número de artículo: 
1442022

MAGIC reveals a complex morphology within the unidentified gamma-ray source HESS J1857+026

Titulo: 
MAGIC reveals a complex morphology within the unidentified gamma-ray source HESS J1857+026
Autores: 
Aleksic, J; Ansoldi, S; Antonelli, LA; Antoranz, P; Babic, A; Bangale, P; de Almeida, UB; Barrio, JA; Gonzalez, JB; Bednarek, W; Bernardini, E; Biland, A; Blanch, O; Bonnefoy, S; Bonnoli, G; Borracci, F; Bretz, T; Carmona, E; Carosi, A; Fidalgo, DC; Colin, P; Colombo, E; Contreras, JL; Cortina, J; Covino, S; Da Vela, P; Dazzi, F; De Angelis, A; De Caneva, G; De Lotto, B; Mendez, CD; Doert, M; Dominguez, A; Prester, DD; Dorner, D; Doro, M; Einecke, S; Eisenacher, D; Elsaesser, D; Farina, E; Ferenc, D; Fonseca, MV; Font, L; Frantzen, K; Fruck, C; Lopez, RJG; Garczarczyk, M; Terrats, DG; Gaug, M; Godinovic, N; Munoz, AG; Gozzini, SR; Hadasch, D; Hayashida, M; Herrera, J; Herrero, A; Hildebrand, D; Hose, J; Hrupec, D; Idec, W; Kadenius, V; Kellermann, H; Klepser, S; Kodani, K; Konno, Y; Krause, J; Kubo, H; Kushida, J; La Barbera, A; Lelas, D; Lewandowska, N; Lindfors, E; Lombardi, S; Lopez, M; Lopez-Coto, R; Lopez-Oramas, A; Lorenz, E; Lozano, I; Makariev, M; Mallot, K; Maneva, G; Mankuzhiyil, N; Mannheim, K; Maraschi, L; Marcote, B; Mariotti, M; Martinez, M; Mazin, D; Menzel, U; Meucci, M; Miranda, JM; Mirzoyan, R; Moralejo, A; Munar-Adrover, P; Nakajima, D; Niedzwiecki, A; Nilsson, K; Nishijima, K; Noda, K; Nowak, N; Wilhelmi, EDO; Orito, R; Overkemping, A; Paiano, S; Palatiello, M; Paneque, D; Paoletti, R; Paredes, JM; Paredes-Fortuny, X; Partini, S; Persic, M; Prada, F; Moroni, PGP; Prandini, E; Preziuso, S; Puljak, I; Reinthal, R; Rhode, W; Ribo, M; Rico, J; Garcia, JR; Rugamer, S; Saggion, A; Saito, T; Saito, K; Satalecka, K; Scalzotto, V; Scapin, V; Schultz, C; Schweizer, T; Shore, SN; Sillanpaa, A; Sitarek, J; Snidaric, I; Sobczynska, D; Spanier, F; Stamatescu, V; Stamerra, A; Steinbring, T; Storz, J; Strzys, M; Sun, S; Suric, T; Takalo, L; Takami, H; Tavecchio, F; Temnikov, P; Terzic, T; Tescaro, D; Teshima, M; Thaele, J; Tibolla, O; Torres, DF; Toyama, T; Treves, A; Uellenbeck, M; Vogler, P; Wagner, RM; Zandanel, F; Zanin, R
Resumen: 
Aims. HESS J1857+026 is an extended TeV gamma-ray source that was discovered by H. E. S. S. as part of its Galactic plane survey. Given its broadband spectral energy distribution and its spatial coincidence with the young energetic pulsar PSR J1856+0245, the source has been put forward as a pulsar wind nebula (PWN) candidate. MAGIC has performed follow-up observations aimed at mapping the source down to energies approaching 100 GeV in order to better understand its complex morphology. Methods. HESS J1857+026 was observed by MAGIC in 2010, yielding 29 h of good quality stereoscopic data that allowed us to map the source region in two separate ranges of energy. Results. We detected very-high-energy gamma-ray emission from HESS J1857+026 with a significance of 12 sigma above 150 GeV. The differential energy spectrum between 100 GeV and 13 TeV is described well by a power law function dN/dE = N-0(E/1TeV)(-Gamma) with N-0 = (5.37 +/- 0.44(stat) +/- 1.5(sys)) X 10(-12) (TeV-1 cm(-2) s(-1)) and Gamma = 2.16 +/- 0.07(stat) +/- 0.15(sys), which bridges the gap between the GeV emission measured by Fermi-LAT and the multi-TeV emission measured by H.E.S.S.. In addition, we present a detailed analysis of the energy-dependent morphology of this region. We couple these results with archival multiwavelength data and outline evidence in favor of a two-source scenario, whereby one source is associated with a PWN, while the other could be linked with a molecular cloud complex containing an HII region and a possible gas cavity.
Autor principal: 
Aleksic, J
Autor/es del IAA: 
Dominguez, A.; Prada, F.; Zandanel, F.
DOI: 
10.1051/0004-6361/201423517
Revista: 
ASTRONOMY & ASTROPHYSICS
Fecha de publicación: 
2014/11
Volumen: 
571
Tipo de documento: 
Article
Palabras clave: 
acceleration of particles; gamma rays: ISM; ISM: clouds; HII regions; ISM: individual objects: HESS J1857+026; pulsars: individual: PSR J1856+0245
Número de artículo: 
A96

Stellar occultation by (119951) 2002 KX14 on April 26, 2012

Titulo: 
Stellar occultation by (119951) 2002 KX14 on April 26, 2012
Autores: 
Alvarez-Candal, A; Ortiz, JL; Morales, N; Jimenez-Teja, Y; Duffard, R; Sicardy, B; Dhillon, VS; Marsh, T; Littlefair, S; Mottola, S; Hellmich, S; Shahbaz, T
Resumen: 
Context. Trans-Neptunian objects (TNOs) are important bodies, but very little is known about their basic physical properties such as size, density, and albedo. Aims. We intend to determine sizes, albedos, and even densities of a good sample of TNOs, especially those of the largest TNOs because they can be studied the best with different observational techniques. Methods. We took advantage of a stellar occultation by (119951) 2002 KX14 to obtain valuable information by means of high temporal resolution CCD imaging using ULTRACAM at the 4.2 m William Herschel Telescope on La Palma (Spain). Results. Thanks to the high time resolution of ULTRACAM and the large aperture provided by the telescope, we recorded the most accurate chord ever obtained for an occultation by a TNO, with a length of 415 +/- 1 km. This is a lower limit to the diameter of (119951) 2002 KX14 assuming that it has a spherical shape. For ellipsoidal objects we developed a method for obtaining equivalent diameters by combining single-chord occultations and accurate astrometry at the time of occultation. By applying this method to (119951) 2002 KX14, we estimate an equal-area equivalent diameter of at least 365(21)(+30) -21 km. A possible upper limit is 455 +/- 27 km, obtained via thermal data. No atmosphere is detected. We obtain a surface temperature higher than 40 K, which precludes the existence of ices, other than water ice, upon the surface, which is consistent with the featureless spectrum of (119951) 2002 KX14. There are no secondary occultation events that could reveal whether there is a ring system, as recently found for the Centaur (10199) Chariklo.
Autor principal: 
Alvarez-Candal, A
Autor/es del IAA: 
Alvarez-Candal, A.; Ortiz, J. L.; Morales, N.; Jimenez-Teja, Y.; Duffard, R.
DOI: 
10.1051/0004-6361/201424648
Revista: 
ASTRONOMY & ASTROPHYSICS
Fecha de publicación: 
2014/11
Volumen: 
571
Tipo de documento: 
Article
Palabras clave: 
methods: analytical; techniques: photometric; occultations; Kuiper belt objects: individual: (119951) 2002 KX14; methods: observational
Número de artículo: 
A48

The Gaia-ESO Survey: alpha-abundances of metal-poor stars

Titulo: 
The Gaia-ESO Survey: alpha-abundances of metal-poor stars
Autores: 
Jackson-Jones, R; Jofre, P; Hawkins, K; Hourihane, A; Gilmore, G; Kordopatis, G; Worley, C; Randich, S; Vallenari, A; Bensby, T; Bragaglia, A; Flaccomio, E; Korn, AJ; Recio-Blanco, A; Smiljanic, R; Costado, MT; Heiter, U; Hill, V; Lardo, C; de Laverny, P; Guiglion, G; Mikolaitis, S; Zaggia, S; Tautvaisiene, G
Resumen: 
We performed a detailed study of the ratio of low-alpha to high-alpha stars in the Galactic halo as observed by the Gaia-ESO Survey. Using a sample of 381 metal-poor stars from the second internal data release, we found that the value of this ratio did not show evidence of systematic trends as a function of metallicity, surface gravity, Galactic latitude, Galactic longitude, height above the Galactic plane, and Galactocentric radius. We conclude that the alpha(poor)/alpha(rich) value of 0.28 +/- 0.08 suggests that in the inner halo, the larger portion of stars were formed in a high star formation rate environment, and about 15% of the metal-poor stars originated from much lower star formation rate environments.
Autor principal: 
Jackson-Jones, R
Autor/es del IAA: 
Costado, M. T.
DOI: 
10.1051/0004-6361/201425099
Revista: 
ASTRONOMY & ASTROPHYSICS
Fecha de publicación: 
2014/11
Volumen: 
571
Tipo de documento: 
Article
Palabras clave: 
stars: abundances; Galaxy: halo
Número de artículo: 
L5

Very Long Baseline polarimetry and the gamma-ray connection in Markarian 421 during the broadband campaign in 2011

Titulo: 
Very Long Baseline polarimetry and the gamma-ray connection in Markarian 421 during the broadband campaign in 2011
Autores: 
Lico, R; Giroletti, M; Orienti, M; Gomez, JL; Casadio, C; D'Ammando, F; Blasi, MG; Cotton, W; Edwards, PG; Fuhrmann, L; Jorstad, S; Kino, M; Kovalev, YY; Krichbaum, TP; Marscher, AP; Paneque, D; Piner, BG; Sokolovsky, KV
Resumen: 
Context. This is the third paper in a series devoted to the analysis of the multiwavelength data from a campaign on the nearby (z = 0.03) TeV blazar Mrk 421 during 2011. Aims. We investigate the structure of the high angular resolution polarization, the magnetic topology, the total intensity light curve, the y-ray.flux, and the photon index. We describe how they evolve and how they are connected. Methods. We analyzed data in polarized intensity obtained with the Very Long Baseline Array (VLBA) at twelve epochs (one observation per month from January to December 2011) at 15, 24, and 43 GHz. For the absolute orientation of the electric vector position angles (EVPA) we used the D-terms method; we also confirm its accuracy. We also used gamma-ray data from the fermi Large Area Telescope on weekly time bins throughout 2011. Results. The source shows polarized emission, and its properties vary with time, frequency, and location along the jet. The core mean polarization fraction is generally between 1% and 2%, with a 4% peak at 43 GHz in March; the polarization angle is variable, mainly at 15 GElz, where it changes frequently, and less so at 43 (H It, where it oscillates in the range 114 degrees -173 degrees. The jet polarization properties are more stable, with a fractional polarization of around 16% and a polarization angle nearly perpendicular to the jet axis. The average flux and photon index at gamma-ray energies are (17.4 +/- 0.5) x10(-8) ph cm(-2) s(-1) and F = 1.77 +/- 0.02. The gamma-ray light curve shows variability, with a main peak of (38 +/- 11) x 10(-8) ph cm(-2) s at the beginning of March and two later peaks centered on September 8 and November 13. The.first gamma-ray peak appears to be associated with the peak in the core polarized emission at 43 Gtlz, as well as with the total intensity light curve. A discrete correlation function analysi.s yields a correlation coefficient of 0.54 at zero delay, with a significance level >99.7%. Conclusions. With this multifrequency study, we accurately determine the polarization properties of Mrk 421, both in the core and in the jet region. The radio and gamma-ray light curves are correlated. The observed.EVPA variability at 15 GHz is partly due to opacity and partly to a variable Faraday rotation effect. To explain the residual variability of the intrinsic polarization angle and the low degree of polarization in the core region, we invoke a blend of variable cross-polarized subcomponents with different polarization properties within the beam.
Autor principal: 
Lico, R
Autor/es del IAA: 
Casadio, C.
DOI: 
10.1051/0004-6361/201424341
Revista: 
ASTRONOMY & ASTROPHYSICS
Fecha de publicación: 
2014/11
Volumen: 
571
Tipo de documento: 
Article
Palabras clave: 
BL Lacertae objects: individual: Mrk 421; galaxies: active; galaxies: jets; galaxies: magnetic fields; techniques: interferometric

Dust environment and dynamical history of a sample of short-period comets II. 81P/Wild 2 and 103P/Hartley 2

Titulo: 
Dust environment and dynamical history of a sample of short-period comets II. 81P/Wild 2 and 103P/Hartley 2
Autores: 
Pozuelos, FJ; Moreno, F; Aceituno, F; Casanova, V; Sota, A; Lopez-Moreno, JJ; Castellano, J; Reina, E; Climent, A; Fernandez, A; Segundo, AS; Hausler, B; Gonzalez, C; Rodriguez, D; Bryssinck, E; Cortes, E; Rodriguez, FA; Baldris, F; Garcia, F; Gomez, F; Limon, F; Tifner, F; Muler, G; Almendros, I; de los Reyes, JA; Henriquez, JA; Moreno, JA; Baez, J; Bel, J; Camarasa, J; Curto, J; Hernandez, JF; Gonzalez, JJ; Martin, JJ; Salto, JL; Lopesino, J; Bosch, JM; Ruiz, JM; Vidal, JR; Ruiz, J; Sanchez, J; Temprano, J; Aymami, JM; Lahuerta, L; Montoro, L; Campas, M; Garcia, MA; Canales, O; Benavides, R; Dymock, R; Garcia, R; Ligustri, R; Naves, R; Lahuerta, S; Pastor, S
Resumen: 
Aims. This paper is a continuation of the first paper in this series, where we presented an extended study of the dust environment of a sample of short-period comets and their dynamical history. On this occasion, we focus on comets 81P/Wild 2 and 103P/Hartley 2, which are of special interest as targets of the spacecraft missions Stardust and EPOXI. Methods. As in the previous study, we used two sets of observational data: a set of images, acquired at Sierra Nevada and Lulin observatories, and the Delta f rho data as a function of the heliocentric distance provided by the amateur astronomical association Cometas-Obs. The dust environment of comets (dust loss rate, ejection velocities, and size distribution of the particles) was derived from our Monte Carlo dust tail code. To determine their dynamical history we used the numerical integrator Mercury 6.2 to ascertain the time spent by these objects in the Jupiter family Comet region. Results. From the dust analysis, we conclude that both 81P/Wild 2 and 103P/Hartley 2 are dusty comets, with an annual dust production rate of 2.8 x 10(9) kg yr(-1) and (0.4-1.5) x 10(9) kg yr(-1), respectively. From the dynamical analysis, we determined their time spent in the Jupiter family Comet region as similar to 40 yr in the case of 81P/Wild 2 and similar to 1000 yr for comet 103P/Hartley 2. These results imply that 81P/Wild 2 is the youngest and the most active comet of the eleven short-period comets studied so far, which tends to favor the correlation between the time spent in JFCs region and the comet activity previously discussed.
Autor principal: 
Pozuelos, FJ
Autor/es del IAA: 
Pozuelos, F. J.; Moreno, F.; Aceituno, F.; Casanova, V.; Sota, A.; Lopez-Moreno, J. J.
DOI: 
10.1051/0004-6361/201424331
Revista: 
ASTRONOMY & ASTROPHYSICS
Fecha de publicación: 
2014/11
Volumen: 
571
Tipo de documento: 
Article
Palabras clave: 
methods: observational; methods: numerical; comets: individual: 81P/Wild 2; comets: individual: 103P/Hartley 2; comets: general
Número de artículo: 
A64

AstroTaverna-Building workflows with Virtual Observatory services

Titulo: 
AstroTaverna-Building workflows with Virtual Observatory services
Autores: 
Ruiz, JE; Garrido, J; Santander-Vela, JD; Sanchez-Exposito, S; Verdes-Montenegro, L
Resumen: 
Despite the long tradition of publishing digital datasets in Astronomy, and the existence of a rich network of services providing astronomical datasets in standardized interoperable formats through the Virtual Observatory (VO), there has been little use of scientific workflow technologies in this field. In this paper we present AstroTaverna, a plugin that we have developed for the Taverna Workbench scientific workflow management system. It integrates existing VO web services as first-class building blocks in Taverna workflows, allowing the digital capture of otherwise lost procedural steps manually performed in e.g. GUI tools, providing reproducibility and re-use. It improves the readability of digital VO recipes with a comprehensive view of the entire automated execution process, complementing the scarce narratives produced in the classic documentation practices, transforming them into living tutorials for an efficient use of the VO infrastructure. The plugin also adds astronomical data manipulation and transformation tools based on the STIL Tool Set and the integration of Aladin VO software, as well as interactive connectivity with SAMP-compliant astronomy tools. (C) 2014 Elsevier B.V. All rights reserved.
Autor principal: 
Ruiz, JE
Autor/es del IAA: 
Ruiz, J. E.; Garrido, J.; Santander-Vela, J. D.; Sanchez-Exposito, S.; Verdes-Montenegro, L.
DOI: 
10.1016/j.ascom.2014.09.002
Revista: 
ASTRONOMY AND COMPUTING
Fecha de publicación: 
2014
Volumen: 
7-8
Páginas: 
3-11
Tipo de documento: 
Article
Palabras clave: 
Virtual observatories; Astroinformatics; Methods: miscellaneous; Astronomical databases: miscellaneous; E-Science; Scientific workflows

How much dark matter is there inside early-type galaxies?

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