Effective collision strengths for transitions in Fe XV

Collision strengths for transitions among the energetically lowest 53 fine-structure levels belonging to the (1s(2)2s(2)2p(6)) 3l(2), 3l3l', 3s4l and 3p4s configurations of Fe XV are computed, over an electron energy range below 160 Ryd, using the Dirac Atomic R-matrix Code (DARC) of Norrington & Grant (2003). Effective collision strengths, obtained after integrating the collision strengths over a Maxwellian distribution of electron energies, have also been calculated. These results of effective collision strengths are tabulated for all 1378 inelastic transitions over a wide temperature range of 10(5) to 10(7) K. Comparisons are also made with other R-matrix calculations and the accuracy of the results is assessed.

Effective collision strengths for transitions among the 3s(2), 3s3p and 3p(2) configurations of Fe xv

Effective collision strengths for transitions among the ten energetically lowest fine-structure levels belonging to the (1s(2)2s(2)2p(6))3s(2), 3s3p and 3p(2) configurations of Fe xv have been calculated in the electron temperature range of 10(5)-10(7) K, using the recent Dirac atomic R-matrix code of Norrington and Grant. The results are compared with the other recently available independent Breit-Pauli R-matrix calculations of Eissner et al (Eissner W, Galavis M E, Mendoza C and Zeippen C J 1999 Astron. Astrophys. Suppl. 137 165) and Griffin et al (Griffin DC, Badnell N R, Pindzola M S and Shaw J A 1999 J. Phys. B: At. Mol. Opt. Phys. 32 2139, 4129). Large differences are observed for many transitions over almost the entire temperature range. These differences are analysed and discussed, and the accuracy of the calculations is assessed.

Oscillator strengths for transitions in C-like ions between FIV and Ar XIII

Energy levels and oscillator strengths (transition probabilities) have been calculated for the fine-structure transitions among the levels of the (1s(2)) 2s(2)2p(2), 2s2p(3), 2p(4), 2s(2)2p3s, 2s(2)2p3p, and 2s(2)2p3d configurations of C-like F IV, Na VI, Al VIII, P X, Cl XII, and Ar XIII using the CIV3 program. The extensive configuration interaction and relativistic effects have been included while generating the wavefunctions. Calculated values of energy levels generally agree within 5% with the experimentally compiled results, and the length and velocity forms of oscillator strengths agree within 20% for a majority of allowed transitions.

Electron impact excitation of A1 XIII: A relativistic approach

Energy levels, radiative rates, collision strengths, and effective collision strengths for all transitions up to and including the n = 5 levels of AlXIII have been computed in the j j coupling scheme including relativistic effects. All partial waves with angular momentum J less than or equal to 60 have been included, and resonances have been resolved in a fine energy grid in the threshold region. Collision strengths are tabulated at energies above thresholds in the range 170.0 less than or equal to E less than or equal to 300.0 Ryd, and results for effective collision strengths, obtained after integrating the collision strengths over a Maxwellian distribution of electron velocities, are tabulated over a wide temperature range of 4.4 less than or equal to log T-e less than or equal to 6.8 K. The importance of including relativistic effects in a calculation is discussed in comparison with the earlier available non-relativistic results.

Electron impact excitation of Al XIII: Collision strengths and rate coefficients

Collision strengths for all transitions up to and including the n = 5 levels of Al XIII have been computed in the LS coupling scheme using the R-matrix code. All partial waves with angular momentum L less than or equal to 45 have been included, and resonances have been resolved in a fine energy grid in the threshold region. Collision strengths are tabulated at energies above thresholds in the range 162.30 less than or equal to E less than or equal to 220.0 Ry, and results for the 1s-2s and 1s-2p transitions are compared with those of previous authors. Additionally, effective collision strengths, obtained after integrating the collision strengths over a Maxwellian distribution of electron velocities, are tabulated over a wide temperature range of 4.40 less than or equal to log T-e less than or equal to 6.40 K.

The extreme-ultraviolet structure and properties of a newly emerged active region

The structure and properties of a newly emerged solar active region (NOAA Active Region 7985) are discussed using the Coronal Diagnostic Spectrometer (CDS) and the Extreme- Ultraviolet Imaging Telescope (EIT) on board the Solar and Heliospheric Observatory. CDS obtained high-resolution EUV spectra in the 308-381 Angstrom and 513-633 Angstrom wavelength ranges, while EIT recorded full-disk EUV images in the He II (304 Angstrom), Fe IX/X (171 Angstrom), Fe xii (195 Angstrom), and Fe XV (284 Angstrom) bandpasses. Electron density measurements from Si rx, Si X, Fe xii, Fe XIII, and Fe xiv line ratios indicate that the region consists of a central high- density core with peak densities of the order of 1.2 x 10(10) cm(-3), which decrease monotonically to similar to5.0 X 10(8) cm(-3) at the active region boundary. The derived electron densities also vary systematically with temperature. Electron pressures as a function of both active region position and temperature were estimated using the derived electron densities and ion formation temperatures, and the constant pressure assumption was found to be an unrealistic simplification. Indeed, the active region is found to have a high-pressure core (1.3 x 10(16) cm(-3) K) that falls to 6.0 x 10(14) cm(-3) K just outside the region. CDS line ratios from different ionization stages of iron, specifically Fe xvi (335.4 Angstrom) and Fe xiv (334.4 Angstrom), were used to diagnose plasma temperatures within the active region. Using this method, peak temperatures of 2.1 x 10(6) K were identified. This is in good agreement with electron temperatures derived using EIT filter ratios and the two-temperature model of Zhang et al. The high- temperature emission is confined to the active region core, while emission from cooler (1-1.6) x 10(6) K lines originates in a system of loops visible in EIT 171 and 195 X images. Finally, the three-dimensional geometry of the active region is investigated using potential field extrapolations from a Kitt Peak magnetogram. The combination of EUV and magnetic field extrapolations extends the "core-halo" picture of active region structure to one in which the core is composed of a number of compact coronal loops that confine the hot, dense, high- pressure core plasma while the halo emission emerges from a system of cooler and more extended loops.

Emission lines of Na-like ions in spectra obtained with the Solar EUV Research Telescope and Spectrograph (SERTS)

Theoretical emission-line ratios involving transitions in the 236-412 Angstrom wavelength range are presented for the Na-like ions Ar viii, Cr xiv, Mn xv, Fe xvi, Co xvii, Ni xviii and Zn xx. A comparison of these with an extensive data set of the solar active region, quiet-Sun, subflare and off-limb observations, obtained during rocket flights by the Solar EUV Research Telescope and Spectrograph (SERTS), reveals generally very good agreement between theory and experiment. This indicates that most of the Na-like ion lines are reliably detected in the SERTS observations, and hence may be employed with confidence in solar spectral analyses. However, the features in the SERTS spectra at 236.34 and 300.25 Angstrom, originally identified as the Ni xviii 3p (2) P-3/2 -3d (2) D- 3/2 and Cr xiv 3p (2) P-3/2 -3d (2) D-5/2 transitions, respectively, are found to be due to emission lines of Ar xiii (236.34 Angstrom) and possibly S v or Ni vi (300.25 Angstrom). The Co xvii 3s (2) S-3p (2) P-3/2 line at 312.55 Angstrom is always badly blended with an Fe xv feature at the same wavelength, but Mn xv 3s (2) S-3p (2) P-1/2 at 384.75 Angstrom may not always be as affected by second-order emission from Fe xii 192.37 Angstrom as previously thought. On the other hand, we find that the Zn xx 3s (2) S-3p (2) P-3/2 transition can sometimes make a significant contribution to the Zn xx/Fe xiii 256.43- Angstrom blend, and hence care must be taken when using this feature as an Fe xiii electron density diagnostic. A line in the SERTS-89 active region spectrum at 265.00 Angstrom has been re-assessed, and we confirm its identification as the Fe xvi 3p (2) P-3/2 -3d (2) D-3/2 transition.

Inner-shell photoexcitation of Fe XV and Fe XVI

The configuration-interaction method as implemented in the computer code CIV3 is used to determine energy levels, electric dipole radiative transition wavelengths, oscillator strengths and transition probabilities for inner-shell excitation of transitions in Fe XV and Fe XVI. Specifically, transitions are considered of the type 1s(2) 2s(2) 2p(6) 3s(2) -1s(2) 2s(2) 2p(5) 3l3l' 3l" (l, l' and l" = s,p or d) in FeXV and 1s(2) 2s(2) 2p(6) 3s- 1s(2) 2s(2) 2p(5) 3l3l' (l and l' = s,p or d) in FeXVI, using the relativistic Breit-Pauli approach. An assessment of the accuracy of the derived atomic data is performed.

An investigation of Fe XV emission lines in solar flare spectra

Previously, large discrepancies have been found between theory and observation for Fe XV emission line ratios in solar flare spectra covering the 224-327 angstrom wavelength range, obtained by the Naval Research Laboratory's S082A instrument on board Skylab. These discrepancies have been attributed to either errors in the adopted atomic data or the presence of additional atomic processes not included in the modelling, such as fluorescence. However our analysis of these plus other S082A flare observations (the latter containing Fe XV transitions between 321-482 angstrom), performed using the most recent Fe XV atomic physics calculations in conjunction with a chianti synthetic flare spectrum, indicate that blending of the lines is primarily responsible for the discrepancies. As a result, most Fe XV lines cannot be employed as electron density diagnostics for solar flares, at least at the spectral resolution of S082A and similar instruments (i.e.similar to 0.1 angstrom). An exception is the intensity ratio I(3s3p P-3(2)-3p(2) P-3(1))/I(3s3p P-3(2)-3p(2) D-1(2))=I(321.8 angstrom)/I(327.0 angstrom), which appears to provide good estimates of the electron density at this spectral resolution.

El conjunto de azulejos nazaríes de principios del siglo XV del Museo Arqueológico de Córdoba

En este trabajo se analiza la iconografía y se concreta la datación y el origen del conjunto de treinta y cinco azulejos nazaríes decorados en cobalto y reflejo metálico procedentes de la que hemos identificado como capilla de Santiago en la antigua iglesia de San Bartolomé, erigida en la Judería de Córdoba tras el asalto de 1391. Se plantea, asimismo, que Diego Fernández Abencaçin, judeoconverso y alfaqueque mayor del rey y presumiblemente el comitente de la capilla funeraria, fue quien adquirió los azulejos. Hasta ahora, la única interpretación de las escenas figuradas que los decoran apuntaba a una supuesta representación de alegorías de los sentidos; no obstante, la comparación con ejemplos paralelos, el estudio de la indumentaria de los personajes y el estilo nos lleva a identificarlas como materialización de los gustos y aficiones de las clases privilegiadas a comienzos del s. XV: el amor cortés, la caza, la fauna, los ministriles –especialmente el ciego acompañado de lazarillo–, las danzarinas y los catadores de vino; costumbres que el alfaqueque conoció durante sus estancias en la corte y en el desempeño de sus obligaciones, no sólo como redentor de cautivos cristianos, sino como trujimán y enviado del infante don Fernando –futuro rey de Aragón– durante la campaña de Antequera ante la corte nazarita de Granada y en las treguas posteriorment e firmadas con Yusuf III, lo que ha posibilitado concretar la datación de los azulejos entre 1410 y 1415.

Joaquim Mir y la tienda de juguetes: microhistoria de un retrato

¿Puede un retrato pictórico suscitar un ejercicio de microhistoria? Nuestra investigación tratará de aportar una respuesta positiva a esta cuestión, analizando para ello uno de los pocos retratos del pintor postimpresionista Joaquim Mir Trinxet, fechado en 1926. El protagonista representado no es otro que el suegro del pintor, Antoni Estalella i Trinxet, un insigne personaje de Vilanova y la Geltrú (Barcelona) que vivió entre dos siglos. La obra está ambientada en la tienda de juguetes de la familia, convirtiéndose así en una de las escasas pinturas que han captado el interior de una juguetería en la España anterior a la Guerra Civil. Gracias a los trabajos de archivo realizados, este artículo reúne diversos documentos inéditos que permiten reconstruir no sólo la vida del retratado, que llegó a ser corresponsal de Francisco Pi y Margall, sino también el ambiente social, artístico y comercial de Vilanova, en un período que abarca desde la década de 1870 a la primera mitad del siglo XX, en plena “Edad de Oro” de la industria juguetera. Es esta una propuesta de metodología historiográfica cuyo recorrido comienza en el oficio arcaico de la tonelería para desembocar al fin en los albores del comercio moderno de juguetes.