Determination of the cross-field density structuring in coronal waveguides using the damping of transverse waves

Time and spatial damping of transverse magnetohydrodynamic (MHD) kink oscillations is a source of information on the cross-field variation of the plasma density in coronal waveguides. We show that a probabilistic approach to the problem of determining the density structuring from the observed damping of transverse oscillations enables us to obtain information on the two parameters that characterise the cross-field density profile. The inference is performed by computing the marginal posterior distributions for density contrast and transverse inhomo- geneity length-scale using Bayesian analysis and damping ratios for transverse oscillations under the assumption that damping is produced by resonant absorption. The obtained distributions show that, for damping times of a few oscillatory periods, low density contrasts and short inho- mogeneity length scales are more plausible in explaining observations. This means that valuable information on the cross-field density profile can be obtained even if the inversion problem, with two unknowns and one observable, is a mathematically ill-posed problem.Comment: 5 pages, 3 figures, accepte

Determination of Transverse Density Structuring from Propagating MHD Waves in the Solar Atmosphere

We present a Bayesian seismology inversion technique for propagating magnetohydrodynamic (MHD) transverse waves observed in coronal waveguides. The technique uses theoretical predictions for the spatial damping of propagating kink waves in transversely inhomogeneous coronal waveguides. It combines wave amplitude damping length scales along the waveguide with theoretical results for resonantly damped propagating kink waves to infer the plasma density variation across the oscillating structures. Provided the spatial dependence of the velocity amplitude along the propagation direction is measured and the existence of two different damping regimes is identified, the technique would enable us to fully constrain the transverse density structuring, providing estimates for the density contrast and its transverse inhomogeneity length scale

Influence of atomic polarization and horizontal illumination on the Stokes profiles of the He I 10830 multiplet

The polarization observed in the spectral lines of the He I 10830 multiplet carries valuable information on the dynamical and magnetic properties of plasma structures in the solar chromosphere and corona, such as spicules, prominences, filaments, emerging magnetic flux regions, etc. Here we investigate the influence of atomic level polarization on the emergent Stokes profiles for a broad range of magnetic field strengths, in both 90 degree and forward scattering geometry. We show that, contrary to a widespread belief, the selective emission and absorption processes caused by the presence of atomic level polarization may have an important influence on the emergent linear polarization, even for magnetic field strengths as large as 1000 G. Consequently, the modeling of the Stokes Q and U profiles should not be done by taking only into account the contribution of the transverse Zeeman effect within the framework of the Paschen-Back effect theory, unless the magnetic field intensity of the observed plasma structure is sensibly larger than 1000 G. We point out also that in low-lying optically thick plasma structures, such as those of active region filaments, the (horizontal) radiation field generated by the structure itself may substantially reduce the positive contribution to the anisotropy factor caused by the (vertical) radiation field coming from the underlying solar photosphere, so that the amount of atomic level polarization may turn out to be negligible. Only under such circumstances may the emergent linear polarization of the He I 10830 multiplet in such regions of the solar atmosphere be dominated by the contribution caused by the transverse Zeeman effect.Comment: Accepted for publication in The Astrophysical Journal (It is tentatively scheduled for the ApJ January 20, 2007 issue

Formas de alteración en materiales antiguos

[Resumen] La presente comunicaclon trata de formas de alteración en afloramientos eruptivos (tipo granito, gabros, diabasas) del litoral lucense. El proceso genético de gran parte del material grueso - a escala de grandes bloques- local izado en frentes pl~ yeros del Cantábrico, se considera como núcleos de alteración intraformables.[Abstract] This paper deals with the phenomenon of spheroidal and ellipsoidal weathering of i gneous rocks; the study has been applied for geographical purpos

Note on the Ribadeo ria subsidence and your relation with the Eo Valley profile

[Resumen] En nuestros estudios sobre la ría de Ribadeo observamos cierta repercusión del hundimiento de este gran accidente geográfico sobre algunos tramos finales del régimen típicamente fluvial; el movimiento de inmersión ·en las proximidades del mar modificó la configuración de la cuenca en la zona de desembocadura; los cambios de nivel que experimentó el frente continental en relación con la formación de la ría tienen un valor muy semejante al sufrido por el cambio de nivel en el perfil transversal policíclico del valle del Eo en el sector fluvial de Naraídos, proximidades de San Tirso de Abres.[Abstract] Tbis note was concerned with the repercussion of the subsidence of the Ribadeo estuary over sorne lands last of the fluvial regimen; the change of deformed shoreline to experiense the continental front in relation with the formation of the estuary, have one value very similar at the enduring by the change level in the profile Eo valley fluvial (sector of Naraídos)

Biodegradación acelerada: ineficaz protección e inoperante actitud en la defensa del medio natural durante el último trienio

[Resumen] En este trabajo se exponen una serie de datos sobre la degradación del medio ambiente. Biodegradación del medio natural, vertidos de crudos de petróleo en zonas costeras de Galicia. Se hacen consideraciones sobre la instalación de plantas industriales en la proximidad de las costas (p. ej. Complejo de San Ciprián); contaminación industrial y energía nuclear: tumba abierta de resíduos nucleares y garantía en la seguridad de la proyectada central nuclear de Regodela-Xove. Palabras finales: las extravagantes campañas de información pública en el «Día mundial del medio ambiente»

Helicoverpa armigera (hübner) (Lepidoptera. Noctuidae): emergencia primaveral de adultos y capturas en trampas de feromonas

Peer Reviewe

Webquest i recursos interactius en xarxa per a la didàctica del patrimoni

Internet és una font inesgotable d'informació que atreu de manera notable els més joves. Els educadors ens hem de posar al dia i aprofitar les possibilitats de la Xarxa i el seu atractiu per transformar-la en una eina al servei de l'ensenyament. Les Webquest acompleixen aquesta missió perfectament, fomentant la cooperació, el bon ús d'Internet i, gràcies al seu plantejament constructivista, fa que tots els alumnes participin en la creació del seu propi coneixement. Veiem què representa Internet en la nostra societat i que son i cóm funcionen les Webquest.Internet es una fuente inagotable de información que atrae de manera notoria a los más jóvenes. Los educadores debemos ponernos al día i aprovechar las posibilidades de la Red y su atractivo, para transformarla en una herramienta al servicio de la enseñanza. Las Webquest cumplen esta misión perfectamente, fomentando la cooperación, el buen uso de Internet y de las herramientas informáticas, y gracias a su planteamiento constructivista, hace que todos los alumnos participen de la creación de su propio conocimiento. Veamos qué representa Internet en nuestra sociedad y que son y como funcionan las Webquest.Internet is an inexhaustible source of information that does attract mostly young people. Educators have to actualize their didactic procedures and have also to take advantage of the possibilities of Internet and its attraction among students for transforming it into a tool for education. Webquests do accomplish this aim, since they foster cooperation, a good use of Internet, and due to their constructivist orientation make possible the participation of students in their own learning process