The high-resolution solar spectrum, 1175-1710 A

Sandlin, G. D.; Bartoe, J. D. F.; Brueckner, G. E.; Tousey, R.; Vanhoosier, M. E.

doi:10.1086/191131

Cited by 154 publications

(119 citation statements)

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“…Del Zanna & Badnell (2016) adopted the wavelengths from Skylab observations at the limb, as reported by Sandlin et al (1986). Their accuracy is about 0.005 Å.…”

Section: Discussion and Summarymentioning

confidence: 99%

“…The first line was directly observed at 1406.059±0.005 Å. The wavelength of the second line was obtained from the 1423.885±0.005 Å decay to the 3s 2 3p 2 P 3/2 , measured by Sandlin et al (1986), and a ground level 3s 2 3p 2 P separation of 951.4 Kaysers, from measurements of the forbidden line in planetary nebulae, see e.g. Feuchtgruber et al (1997).…”

Section: Discussion and Summarymentioning

confidence: 99%

“…In turn, these values are minor revisions of an earlier work (Edlén 1981), which was mainly based on the experimental observations of Bromander (1969), who used a very large (3m focal length) spectrograph and measured the wavelengths to better than 0.01 Å. Since then, better solar rest wavelengths were obtained by Sandlin et al (1986) The CHIANTI wavelengths were revised in version 7.1 (Landi et al 2013), to include the values obtained by Young et al (2011) using HST/STIS RR Tel spectra. This revision caused some confusion in the literature, especially regarding the wavelength of the line blended with S iv, estimated by Young et al (2011) at 1404.779 Å.…”

Section: Appendix A2: O IVmentioning

confidence: 99%

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Density diagnostics derived from the O iv and S iv intercombination lines observed by IRIS

Polito

Zanna

Dudík

et al. 2016

A&A

100

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The intensity of the O iv 2s 2 2p 2 P-2s2p 2 4 P and S iv 3 s 2 3p 2 P-3s 3p 2 4 P intercombination lines around 1400 Å observed with the Interface Region Imaging Spectrograph (IRIS) provide a useful tool to diagnose the electron number density (N e ) in the solar transition region plasma. We measure the electron number density in a variety of solar features observed by IRIS, including an active region (AR) loop, plage and brightening, and the ribbon of the 22-June-2015 M 6.5 class flare. By using the emissivity ratios of O iv and S iv lines, we find that our observations are consistent with the emitting plasma being near isothermal (logT [K] ≈ 5) and iso-density (N e ≈ 10 10.6 cm −3 ) in the AR loop. Moreover, high electron number densities (N e ≈ 10 13 cm −3 ) are obtained during the impulsive phase of the flare by using the S iv line ratio. We note that the S iv lines provide a higher range of density sensitivity than the O iv lines. Finally, we investigate the effects of high densities (N e 10 11 cm −3 ) on the ionization balance. In particular, the fractional ion abundances are found to be shifted towards lower temperatures for high densities compared to the low density case. We also explored the effects of a non-Maxwellian electron distribution on our diagnostic method.

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“…Del Zanna & Badnell (2016) adopted the wavelengths from Skylab observations at the limb, as reported by Sandlin et al (1986). Their accuracy is about 0.005 Å.…”

Section: Discussion and Summarymentioning

confidence: 99%

Section: Discussion and Summarymentioning

confidence: 99%

Section: Appendix A2: O IVmentioning

confidence: 99%

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Density diagnostics derived from the O iv and S iv intercombination lines observed by IRIS

Polito

Zanna

Dudík

et al. 2016

A&A

100

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“…If available, unidentified lines are characterized by the temperature classification of Feldman et al (1997) (a): T e < 3 × 10 5 K, (b): T e ≈ 3 × 10 5 K, (c): T e ≈ 4 × 10 5 K, (d): 6 × 10 5 K < T e < 9 × 10 5 K, (e): T e ≈ 1.4 × 10 6 K, (f): T e ≈ 1.8 × 10 6 K. The line intensities are given in the unit of mW sr −1 m −2 . References in last column: (0) Curdt et al (Curdt et al (2001)), (1) Ekberg & Feldman (Ekberg & Feldman (2003)), (2) Sandlin et al (Sandlin et al (1986) …”

Section: Discussionmentioning

confidence: 99%

“…The H 2 emission is extremely weak in the quiet Sun (Sandlin et al 1986). It was also observed in flares (Bartoe et al 1979) and microflares in the active region plage (Innes 2008).…”

Section: Peculiar Lines In the Sunspotmentioning

confidence: 99%

Solar transition region above sunspots

Curdt

Teriaca

Landi

et al. 2009

A&A

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Aims. We study the transition region (TR) properties above sunspots and the surrounding plage regions, by analyzing several sunspot reference spectra obtained by the SUMER (Solar Ultraviolet Measurements of Emitted Radiation) instrument in March 1999 and November 2006. Methods. We compare the SUMER spectra observed in the umbra, penumbra, plage, and sunspot plume regions. The hydrogen Lyman line profiles averaged in each of the four regions are presented. For the sunspot observed in 2006, the electron densities, differential emission measure (DEM), and filling factors of the TR plasma in the four regions are also investigated.Results. The self-reversals of the hydrogen Lyman line profiles are almost absent in sunspots at different locations (at heliocentric angles of up to 49 • ) on the solar disk. In the sunspot plume, the Lyman lines are also not reversed, whilst the lower Lyman line profiles observed in the plage region are obviously reversed, a phenomenon found also in the normal quiet Sun. The TR densities of the umbra and plume are similar and one order of magnitude lower than those of the plage and penumbra. The DEM curve of the sunspot plume exhibits a peak centered at log(T/K) ∼ 5.45, which exceeds the DEM of other regions by one to two orders of magnitude at these temperatures. We also find that more than 100 lines, which are very weak or not observed anywhere else on the Sun, are well observed by SUMER in the sunspot, especially in the sunspot plume. Conclusions. We suggest that the TR above sunspots is higher and probably more extended, and that the opacity of the hydrogen lines is much lower above sunspots, compared to the TR above plage regions. Our result indicates that the enhanced TR emission of the sunspot plume is probably caused by a large filling factor. The strongly enhanced emission at TR temperatures and the reduced continuum ensure that many normally weak TR lines are clearly distinctive in the spectra of sunspot plumes.

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3.1.1.3 Solar energy spectrum

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Instruments, Methods, Solar System

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The high-resolution solar spectrum, 1175-1710 A

Cited by 154 publications

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Density diagnostics derived from the O iv and S iv intercombination lines observed by IRIS

Density diagnostics derived from the O iv and S iv intercombination lines observed by IRIS

Solar transition region above sunspots

3.1.1.3 Solar energy spectrum

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