Magnetic field variations associated with umbral flashes and penumbral waves

Umbral flashes (UF) and running penumbral waves (RPWs) in sunspot chromospheres leave a dramatic imprint in the intensity profile of the Ca II 854.2 nm line. Recent studies have focussed on also explaining the observed polarization profiles, that show even more dramatic variations during the passage of these shock fronts. While most of these variations can be explained with an almost constant magnetic field as a function of time, several studies have reported changes in the inferred magnetic field strength during UF phases. In this study we investigate the origin of these periodic variations of the magnetic field strength by analyzing a time-series of high temporal cadence observations acquired in the Ca II line with the CRISP instrument at the Swedish 1-m Solar Telescope. In particular, we analyze how the inferred geometrical height scale changes between quiescent and UF phases, and whether those changes are enough to explain the observed changes in $B$. We have performed non-LTE data inversions with the NICOLE code of a time-series of very high spatio-temporal resolution observations in the Ca II and Fe I 630.15\630.25 nm lines. Our results indicate that the Ca II line in sunspots is greatly sensitive to magnetic fields at $\log\tau_{500}=-5$ during UFs and quiescence. However, this optical depth value does not correspond to the same geometrical height during the two phases. Our results indicate that during UFs and RPWs the $\log\tau=-5$ is located at a higher geometrical height than during quiescence. Additionally, the inferred magnetic field values are higher in UFs (~270 G) and in RPWs (~100 G). Our results suggest that opacity changes caused by UFs and RPWs cannot explain the observed temporal variations in the magnetic field, as the line seems to form at higher geometrical heights where the field is expected to be lower.Comment: Accepted in A&

The chromosphere above a δ\delta-sunspot in the presence of fan-shaped jets

$\delta$-sunspots are known to be favourable locations for fast and energetic events like flares and CMEs. The photosphere of this type of sunspots has been thoroughly investigated in the past three decades. The atmospheric conditions in the chromosphere are not so well known, however. his study is focused on the chromosphere of a $\delta$-sunspot that harbours a series of fan-shaped jets in its penumbra . The aim of this study is to establish the magnetic field topology and the temperature distribution in the presence of jets in the photosphere and the chromosphere. We use data from the Swedish 1-m Solar Telescope (SST) and the Solar Dynamics Observatory. We invert the spectropolarimetric FeI 6302~\AA\ and CaII ~8542~\AA\ data from the SST using the the non-LTE inversion code NICOLE to estimate the magnetic field configuration, temperature and velocity structure in the chromosphere. A loop-like magnetic structure is observed to emerge in the penumbra of the sunspot. The jets are launched from the loop-like structure. Magnetic reconnection between this emerging field and the pre-existing vertical field is suggested by hot plasma patches on the interface between the two fields. The height at which the reconnection takes place is located between $\log \tau_{500} = -2$ and $\log \tau_{500} = -3$. The magnetic field vector and the atmospheric temperature maps show a stationary configuration during the whole observation.Comment: 12 pages, 15 figures. Recommended for publication in A&

Lecturas e ideas en Nueva España.

Sin resume

La cátedra de Escoto en México, siglo XVIII

Ponencia en las V Jornadas sobre la presencia universitaria española en América: universidad y colegios universitarios en la época postcolonial (1760-1830). Alcalá de Henares, Noviembre de 1991

Estación de capturación de energía solar térmica para planta de potencia

En el presente Trabajo de Fin de Grado se plantea la posibilidad de usar la energía calorífica que nos suministra diariamente el Sol como fuente de energía primaria. Su extracción tiene lugar con captadores solares, del tipo cilíndrico parabólico, sobredimensionados un 10% para poder crear un excedente energético. Este se almacena en un sistema de acumulación hábil durante 24 horas, con vistas a recurrir a él en caso de permanentes condiciones climatológicas adversas. Se obtiene un campo solar de 22 hectáreas y 680 módulos captadores.Traballo fin de grao (UDC.EPS). Enxeñaría en tecnoloxías industriais. Curso 2016/201

Permutation Tests

In this Bachelor dissertation permutation tests are reviewed both theoretically and practically. Chapter 1 is a brief introduction to set the reader on the starting point of this project. Non-parametric methods and some basic concepts would be defined. Chapter 2 is the theoretical core of this dissertation. Permutation techniques are exhaustively introduced, as well as the construction of tests based on this idea, the behaviour of p-values, a succinct review of the critical region and an overview of permutational equivalence. Chapter 3 complements the previous chapter as theoretical framework development continues. Test unbiasedness, con ditional power function, confidence intervals and general asymptotic properties are illustrated here. Finally, Chapter 4 shows some practical experiments where theoretical concepts approached in Chapters 2 and 3 are applied to real-world scenarios.En este trabajo se presentan los tests de permutaciones de forma tanto teórica como práctica. El Capítulo 1 es una breve introducción para situar al lector en el punto de partida del proyecto. Se definen los métodos no paramétricos y algunos conceptos claves. El Capítulo 2 es el núcleo teórico del ensayo. Las técnicas de permutaciones se explican en profundidad, así como la construcción de tests basados en esta idea, el comportamiento de su p-valor, una breve introducción de la región crítica y el concepto de equivalencia permutacional. El Capítulo 3 complementa el capítulo anterior continuando el desarrollo teórico. La insesgadez de los tests, la función potencia condicionada, intervalos de confianza y algunas propiedades asintóticas generales son los protagonistas de esta parte. Finalmente, en el Capítulo 4 se exponen algunos experimentos prácticos donde los conceptos teóricos analizados previamente en los capítulos 2 y 3 se aplican a casos reales.Universidad de Sevilla. Grado en Matemática

Reproducible SUmmation under HUB Format

Version diferente del paper presentado en el congresoFloating point reproducibility is a property claimed by programmers and end users. Half-Unit-Biased (HUB) is a new representation format in which the round to nearest is carried out by truncation, preventing any carry propagation and saving time and area. In this paper we study the reproducible summation of HUB numbers by using a errorfree vector transformation technique, providing both a specific architecture and the usage of combined HUB/Standard floating point adders to achieve a reproducible resultUniversidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

The effect of isotopic splitting on the bisector and inversions of the solar Ca II 854.2 nm line

The Ca II 854.2 nm spectral line is a common diagnostic of the solar chromosphere. The average line profile shows an asymmetric core, and its bisector shows a characteristic inverse-C shape. The line actually consists of six components with slightly different wavelengths depending on the isotope of calcium. This isotopic splitting of the line has been taken into account in studies of non-solar stars, but never for the Sun. We performed non-LTE radiative transfer computations from three models of the solar atmosphere and show that the asymmetric line-core and inverse C-shape of the bisector of the 854.2 nm line can be explained by isotopic splitting. We confirm this finding by analysing observations and showing that the line asymmetry is present irrespective of conditions in the solar atmosphere. Finally, we show that inversions based on the Ca II 854.2 nm line should take the isotopic splitting into account, otherwise the inferred atmospheres will contain erroneous velocity gradients and temperatures.Comment: Accepted for ApJ