IRIS Observations of the Mg II h & k Lines During a Solar Flare

The bulk of the radiative output of a solar flare is emitted from the chromosphere, which produces enhancements in the optical and UV continuum, and in many lines, both optically thick and thin. We have, until very recently, lacked observations of two of the strongest of these lines: the Mg II h & k resonance lines. We present a detailed study of the response of these lines to a solar flare. The spatial and temporal behaviour of the integrated intensities, k/h line ratios, line of sight velocities, line widths and line asymmetries were investigated during an M class flare (SOL2014-02-13T01:40). Very intense, spatially localised energy input at the outer edge of the ribbon is observed, resulting in redshifts equivalent to velocities of ~15-26km/s, line broadenings, and a blue asymmetry in the most intense sources. The characteristic central reversal feature that is ubiquitous in quiet Sun observations is absent in flaring profiles, indicating that the source function increases with height during the flare. Despite the absence of the central reversal feature, the k/h line ratio indicates that the lines remain optically thick during the flare. Subordinate lines in the Mg II passband are observed to be in emission in flaring sources, brightening and cooling with similar timescales to the resonance lines. This work represents a first analysis of potential diagnostic information of the flaring atmosphere using these lines, and provides observations to which synthetic spectra from advanced radiative transfer codes can be compared.Comment: 12 pages, 14 figures, Accepted for publication in Astronomy and Astrophysic

The spectral content of SDO/AIA 1600 and 1700 \AA\ filters from flare and plage observations

The strong enhancement of the ultraviolet emission during solar flares is usually taken as an indication of plasma heating in the lower solar atmosphere caused by the deposition of the energy released during these events. Images taken with broadband ultraviolet filters by the {\em Transition Region and Coronal Explorer} (TRACE) and {\em Atmospheric Imaging Assembly} (AIA 1600 and 1700~\AA) have revealed the morphology and evolution of flare ribbons in great detail. However, the spectral content of these images is still largely unknown. Without the knowledge of the spectral contribution to these UV filters, the use of these rich imaging datasets is severely limited. Aiming to solve this issue, we estimate the spectral contributions of the AIA UV flare and plage images using high-resolution spectra in the range 1300 to 1900~\AA\ from the Skylab NRL SO82B spectrograph. We find that the flare excess emission in AIA 1600~\AA\ is { dominated by} the \ion{C}{4} 1550~\AA\ doublet (26\%), \ion{Si}{1} continua (20\%), with smaller contributions from many other chromospheric lines such as \ion{C}{1} 1561 and 1656~\AA\ multiplets, \ion{He}{2} 1640~\AA, \ion{Si}{2} 1526 and 1533~\AA. For the AIA 1700~\AA\ band, \ion{C}{1} 1656~\AA\ multiplet is the main contributor (38\%), followed by \ion{He}{2} 1640 (17\%), and accompanied by a multitude of other, { weaker} chromospheric lines, with minimal contribution from the continuum. Our results can be generalized to state that the AIA UV flare excess emission is of chromospheric origin, while plage emission is dominated by photospheric continuum emission in both channels.Comment: Accepted for publication in ApJ Skylab NRL SO82B data used in this work available at http://dx.doi.org/10.5525/gla.researchdata.68

O mercado de luxo e o marketing holístico: o caso dos hotéis de luxo

No atual contexto económico de crise, o mercado de luxo conseguiu cresceu, porque muitos dos clientes de luxo mantêm o poder financeiro e conservam a sua ambição por luxo. No entanto, num mercado caracterizado por intensa concorrência não é suficiente ter uma marca forte, é imprescindível acrescentar valor e o marketing holístico pode contribuir fortemente para esse resultado. Nesse sentido, o objetivo deste artigo é analisar as especificidades do mercado de luxo comparativamente com o mercado de bens comuns, e avaliar o nível de valorização e aplicação pelas marcas de luxo de cada uma das quatro dimensões do marketing holístico (marketing relacional, marketing interno, marketing performance e marketing integrado). Para o efeito foi escolhido o setor de turismo de luxo português, mais concretamente, os hotéis de luxo. Os dados foram recolhidos por via da realização de entrevistas aos diretores hoteleiros ou gestores de marketing de seis hotéis de luxo localizados em Portugal e foram tratados seguindo uma metodologia qualitativa de análise temática de conteúdo por recurso ao software MAXqda®. Os resultados denotam que o mercado de luxo é mais complexo de gerir do que o mercado de bens comuns e realçam que os hotéis de luxo privilegiam cada uma das dimensões inerentes à filosofia de marketing holístico. Este artigo faculta informações importantes que podem contribuir para as recentes teorias e práticas de marketing no mercado de luxo