Atomic physics calculations relevant to solar flare spectra

1991 ◽  
Vol 336 (1643) ◽  
pp. 471-484 ◽  
Keyword(s):  
Solar Flare ◽  
Atomic Physics ◽  
Solar Flares ◽  
Solar Maximum ◽  
Emission Lines ◽  
Atomic Data ◽  
Solar Maximum Mission ◽  
X Ray ◽  
Physical Conditions ◽  
Recombination Processes

Solar flare spectra in the ultraviolet and X-ray wavelength regions are rich in emission lines from highly ionized ions, formed at temperatures around 10 7 K. These lines can be used as valuable diagnostics for probing the physical conditions in solar flares. Such analyses require accurate atomic data for excitation, ionization and recombination processes. In this paper, we present a review of work which has already been carried out, in particular for the Solar Maximum Mission observations, and we look to future requirements for Solar-A .

The role of magnetic loops in solar flares

1991 ◽  
Vol 336 (1643) ◽  
pp. 389-400 ◽  
Keyword(s):  
Solar Flare ◽  
Spatial Structure ◽  
Spatial Resolution ◽  
Solar Flares ◽  
Solar Maximum ◽  
Magnetic Topology ◽  
Solar Maximum Mission ◽  
X Ray ◽  
Ultraviolet Observations

X -ray and ultraviolet observations of flares have provided much important information on their spatial structure and magnetic topology. The early observations from Skylab emphasized the role of simple loops and loop arcades, but later observations from the Solar Maximum Mission have greatly complicated this picture. Flares appear in a multitude of loops with complex spatial and temporal interrelations. In many cases, interactions between different loops appear to play a crucial role. The inferred magnetic topology of solar flares will be reviewed with emphasis on the implications for processes of energy release and transfer. It will be shown that the spatial resolution of the observations obtained so far is still inadequate for solving many basic questions of solar flare research.

scholarly journals Preface

1991 ◽  
Vol 336 (1643) ◽  
pp. 323-323
Keyword(s):  
Solar Flare ◽  
Energy Release ◽  
Gamma Rays ◽  
Solar Flares ◽  
Solar Maximum ◽  
Interplanetary Space ◽  
Release Site ◽  
Solar Maximum Mission ◽  
New Information ◽  
Three Space

During the period of the 1980 solar maximum three space missions (P78-1, Solar Maximum Mission and Hinotori ) carried out extensive studies of solar flares. In their different ways all of these missions contributed significant new information to our understanding of the solar flare phenomenon. In this volume the contribution made by these three spacecraft to the study of the energy release and the related creation of high-tem perature plasma, the transport of energy from the primary release site, the production of gamma-rays at energies up to 10 MeV and the ejection of solar matter into interplanetary space are reviewed.

scholarly journals X-Ray and EUV Spectra of Solar Flares and Laboratory Plasmas

1975 ◽  
Vol 68 ◽  
pp. 165-181 ◽  
Author(s):  
G. A. Doschek
Keyword(s):  
Solar Flare ◽  
Solar Flares ◽  
Emission Lines ◽  
Laboratory Work ◽  
Iron Ions ◽  
X Ray ◽  
Laboratory Plasmas ◽  
Euv Spectrum ◽  
Recent Laboratory

Recent laboratory work relevant to solar flares on the spectroscopy of highly ionized atoms is reviewed. Much of this work has concerned the X-ray and EUV spectrum of iron ions, Fe XVIII–Fe XXIV, which produce prominent emission lines in the spectra of solar flares. Also discussed are recently obtained laboratory X-ray spectra of emission lines of hydrogen-like and helium-like ions, and associated satellite lines due to transitions of the type, 1s2l—2p2l, 1s22l—1s2p2l, and 1s22l— —1s2l3p. Satellite lines have also been identified in spectra of solar flares, and can be used to determine the electron temperature of the plasma. The laboratory work is important in the planning of future experiments in solar flare X-ray and EUV spectroscopy.

scholarly journals Atomic Physics Calculations for Iron L-line Spectra

2005 ◽  
Vol 13 ◽  
pp. 627-629
Author(s):  
Jacques Dubau ◽  
Delphine Porquet ◽  
Oleg Zabaydullin
Keyword(s):  
Solar Corona ◽  
Atomic Physics ◽  
Theoretical Approach ◽  
Emission Lines ◽  
Atomic Data ◽  
Iron Ions ◽  
X Ray ◽  
Upper Level ◽  
New Generation

AbstractAbsorption L-lines of iron ions are observed, in spectra of Seyfert 1 galaxies by the new generation of X-ray satellites: Chandra and XMM-Newton. Lines associated to Fe 23+ to Fe16+ have been already observed in emission, in the solar corona and in laboratory. Whereas, those corresponding to Fe 15+ to Fe6+ have not been observed as emission lines, the upper level of the transition decaying preferentially by autoionization. Many atomic data are available for the first ion set. For the second set, some data have been recently published for n=2 to n’=3 transitions. We have recalculated them using another theoretical approach and have extended them to n’=4.

Solar flare X-ray spectra from the Solar Maximum Mission Flat Crystal Spectrometer

1982 ◽  
Vol 256 ◽  
pp. 774 ◽  
Author(s):  
K. J. H. Phillips ◽  
B. C. Fawcett ◽  
B. J. Kent ◽  
A. H. Gabriel ◽  
J. W. Leibacher ◽  
...  
Keyword(s):  
Solar Flare ◽  
Solar Maximum ◽  
Crystal Spectrometer ◽  
Solar Maximum Mission ◽  
X Ray

The Comparison of Helium-Like Ion Emission Line Ratios with Solar X-Ray Spectral Data

1988 ◽  
Vol 102 ◽  
pp. 331-334
Author(s):  
S.M. McCann ◽  
F.P. Keenan
Keyword(s):  
Emission Line ◽  
Solar Flares ◽  
Solar Maximum ◽  
Impact Excitation ◽  
Electron Impact Excitation ◽  
Temperature Sensitive ◽  
Solar Maximum Mission ◽  
X Ray ◽  
Low Density Limit ◽  
Ion Emission

AbstractElectron impact excitation rates recently calculated by Keenan, McCann and Kingston for transitions in the He-like ions Al XII, Si XIII and S XV are used to derive the electron temperature sensitive emission line ratio G and the density sensitive ratio R in its low density limit (Ro). These ratios are compared with those calculated by other authors and with the values obtained for solar flares using instruments on board the P78-1 and Solar Maximum Mission satellites. In general it is found that our results resolve discrepancies which currently exist between observation and theory, which provides experimental support for the methods and atonic data adopted in the present analysis.

scholarly journals Derivation of the Ionization Balance for Iron XIV/XXV and XXIII/XXIV Using Solar X-Ray Data

1984 ◽  
Vol 86 ◽  
pp. 13-16
Author(s):  
E. Antonucci ◽  
M.A. Dodero ◽  
A.H. Gabriel ◽  
K. Tanaka
Keyword(s):  
Solar Flares ◽  
Solar Maximum ◽  
Plasma Electron ◽  
Large Set ◽  
Spectral Emission ◽  
Crystal Spectrometer ◽  
X Ray ◽  
Physical Conditions ◽  
Bent Crystal ◽  
Ionization Balance

The relative concentrations of different ionization stages of iron are measured using the spectral emission of plasmas formed during solar flares. This is an extension of a study on the ionization balance of heavy elements, initiated with the analysis of calcium solar spectra (Antonucci et al., 1984). The data consist of a large set of iron spectra in the wavelength range from 1.84 to 1.88 Å, detected during the recent maximum of activity with the X-ray Polychromator Bent Crystal Spectrometer (BCS) on the NASA Solar Maximum Mission satellite and on the Soft X-ray Crystal Spectrometer (SOX) on the Hinotori satellite.At the low densities typical of the solar corona, in the steady state the ionization balance of an element is a function of the plasma electron temperature. Hence, it can be measured for plasmas of known temperature and in slowly varying physical conditions, and in most cases, solar flare plasmas can be considered to be in such conditions.

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