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

Phillips, K. J. H.; Fawcett, B C; Kent, B. J.; Gabriel, A. H.; Leibacher, J. W.; Wolfson, C. J.; Acton, L. W.; Parkinson, J. H.; Culhane, J. L.; Mason, H. E.

doi:10.1086/159950

Cited by 137 publications

(89 citation statements)

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“…We reviewed the measurements of X-ray wavelengths found in the literature, and found that Hutcheon et al (1976a) and Hutcheon et al (1976b) provide very accurate values. There is excellent agreement, within 1 m Å, between the Hutcheon et al measurements and the most accurate measurements in the X-rays, from laboratory spectra (Boiko et al 1978) to solar SMM/FCS ones (Phillips et al 1982).…”

Section: X-ray Observationssupporting

confidence: 61%

Benchmarking atomic data for astrophysics: Fe XVII EUV lines

Zanna¹,

Ishikawa

2009

A&A

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In the light of accurate structure and scattering calculations for Fe xvii, we review the status of identifications in the EUV spectrum of this ion using various experimental data, from the X-rays to the UV. Most previous identifications are confirmed, although a critical revision leads to changes in many wavelength values, in particular for the 2p 5 3s-2p 5 3p and 2p 5 3p-2p 5 3d transitions, which we observed with the Hinode EUV Imaging Spectrometer (EIS). Several lines are identified here for the first time. We find good agreement between expected and measured line intensities, with a few notable exceptions. In particular, the strong line in the EIS spectra, observed at 254.88 Å, has a consistently low observed intensity. We present two Hinode/EIS observations and discuss which lines are clearly blended in these datasets, and which are reliable for diagnostic purposes.

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Section: X-ray Observationssupporting

confidence: 61%

Benchmarking atomic data for astrophysics: Fe XVII EUV lines

Zanna¹,

Ishikawa

2009

A&A

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“…This is in excellent agreement with the wavelength of a line observed with the SMM/FCS at 16.337 Å (Phillips et al 1982). Brown et al (1998) observed the line at 16.350 ± 0.008 Å, so it appears that this measurement is inaccurate.…”

Section: X-ray Observationssupporting

confidence: 75%

“…We reviewed the measurements of X-ray wavelengths found in the literature, and found that Hutcheon et al (1976a) and Hutcheon et al (1976b) give very accurate values. There is excellent agreement, within 1 mÅ, between the Hutcheon et al measurements and the most accurate measurements in the X-rays, from laboratory spectra (Boiko et al 1978) to solar SMM/FCS ones (Phillips et al 1982). The assessed level energies have been presented in Del Zanna & Ishikawa (2009).…”

Section: The Benchmark Methods and Atomic Datasupporting

confidence: 60%

Benchmarking atomic data for astrophysics: Fe XVII X-ray lines

Zanna¹

2011

A&A

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Recent R-matrix scattering calculations for electron impact excitation of Fe xvii are benchmarked against various X-ray solar observations. Quiescent active region observations are considered, together with a few SMM/FCS observations of active regions and flares analysed here. Extremely good agreement (within 10%) between expected and measured line intensities is found, with the exception of a few weaker lines that appear to be blended, and without the need to invoke opacity effects in the stronger line. The long-standing discrepancies that have been present when distorted wave (DW) calculations are adopted are now finally resolved. As was shown in the Fe xviii case, the differences with the DW calculations are caused by resonances that significantly increase the collision strengths of the 2p-3s transitions. The strong Fe xvii lines can now be reliably used to measure electron temperatures in the solar corona and other astrophysical sources. Emission measure modelling with the most recent atomic data of quiescent active region cores indicates O/Fe and Ne/Fe abundances reduced by factors of two to four compared to the latest compilation of "photospheric" abundances.

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“…In both the Capella and HR 1099 HETGS spectra there is a feature near 7.17 Å , which in HR 1099 is of comparable strength to the Al xii resonance line. Solar X-ray spectra from the Solar Maximum Mission (SMM) and SOLEX also show no feature at 7.22 Å ; instead, they identify a feature at 7.17 Å as Al xiii (Phillips et al 1982;McKenzie et al 1985). The energy levels of Erickson (1977) and Mohr (1985) predict wavelengths of 7.171 and 7.176 Å for the 2 S 1/2 -2 P 3/2 and 2 S 1/2 -2 P 1/2 transitions, respectively.…”

Section: -(A)mentioning

confidence: 99%

Chandra,Extreme Ultraviolet Explorer, and Very Large Array Observations of the Active Binary System σ²Coronae Borealis

Osten

Ayres

Brown

et al. 2003

ApJ

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We present the results of a coordinated observing campaign on the short-period RS CVn binary 2 Coronae Borealis (F6V þ G0V; P orb ¼ 1:14 days) with the Very Large Array, the Extreme Ultraviolet Explorer, and the Chandra X-Ray Observatory High-Energy Transmission Grating Spectrometer. The radio emission is consistent with previously determined quiescent gyrosynchrotron properties. Multiple flares were seen with Extreme Ultraviolet Explorer, five occurring within two consecutive orbital periods. The first of these flares was observed with Chandra. The Chandra observations of 2 CrB showed no systematic variations of line fluxes, widths, or Doppler shifts with orbital phase, nor any response in line width or offset due to the flare. This is consistent with both stars being equally active coronal emitters. We have developed a self-consistent method of spectral analysis to derive information from the line and continuum emissions concerning the distribution of plasma with temperature and elemental abundances. A bimodal temperature distribution is appropriate for both quiescent and flare intervals, with a stable peak at 6-8 MK and another variable enhancement at higher temperatures, with evidence for significant contribution from temperatures up to 50 MK during the flare, compared to 30 MK during quiescence. The iron abundance is subsolar during quiescence but is enriched by about a factor of 2 during a large flare seen with Chandra. The noble gas elements neon and argon show elevated abundances with respect to iron, but there is no clear evidence for any first ionization potential-based abundance pattern during quiescence or the flare. We have determined coronal electron densities from the helium-like ions O vii, Ne ix, Mg xi, and Si xiii, which imply densities !10 10 cm À3 . There is a small enhancement in the electron densities derived for the flare, but it is not statistically significant. We call attention to electron temperature constraints provided by the ratios of 1s 2 1 S 0 -1snp 1 P 1 transitions of the helium-like ions O vii, Ne ix, Mg xi, and Si xiii. The derived coronal electron pressures change by 1-2 orders of magnitude over a 25% change in temperature, implying nonisobaric coronal conditions. We find no evidence for significant departures from the effectively thin coronal assumption. The electron densities inferred from the soft X-ray spectra are inconsistent with cospatial gyrosynchrotron emission; further observations are necessary to discriminate the relative locations of the radio and soft X-ray-emitting plasma.

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

Cited by 137 publications

References 0 publications

Benchmarking atomic data for astrophysics: Fe XVII EUV lines

Benchmarking atomic data for astrophysics: Fe XVII EUV lines

Benchmarking atomic data for astrophysics: Fe XVII X-ray lines

Chandra,Extreme Ultraviolet Explorer, and Very Large Array Observations of the Active Binary System σ²Coronae Borealis

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

Cited by 137 publications

References 0 publications

Benchmarking atomic data for astrophysics: Fe XVII EUV lines

Benchmarking atomic data for astrophysics: Fe XVII EUV lines

Benchmarking atomic data for astrophysics: Fe XVII X-ray lines

Chandra,Extreme Ultraviolet Explorer, and Very Large Array Observations of the Active Binary System σ2Coronae Borealis

Contact Info

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Chandra,Extreme Ultraviolet Explorer, and Very Large Array Observations of the Active Binary System σ²Coronae Borealis