Sub-arcsecond observations of the solar X-ray corona

Golub, L.; Herant, Marc; Kalata, K.; Lovas, I.; Nystrom, G.; Pardo, Francisco S.; Spiller, Eberhard; Wilczyńskí, J.

doi:10.1038/344842a0

Cited by 160 publications

(52 citation statements)

References 10 publications

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“…With the sounding rocket payload Normal Incidence X-ray Telescope (NIXT), Golub et al (1990) observed, with very high spatial resolution, a few bright points at 6.35 nm in the lines of Mg X and Fe XVI and found bipolar magnetic structures. Comparison of NIXT observations with those of the Soft X-ray Telescope (SXT) on Yohkoh indicated that these compact loop structures had a low filling factor (Di Matteo et al 1999).…”

Section: Bright Pointsmentioning

confidence: 99%

Observations of the Sun at Vacuum-Ultraviolet Wavelengths from Space. Part II: Results and Interpretations

et al. 2007

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In Part I of this review, the concepts of solar vacuum-ultraviolet (VUV) observations were outlined together with a discussion of the space instrumentation used for the investigations. A section on spectroradiometry provided some quantitative results on the solar VUV radiation without considering any details of the solar phenomena leading to the radiation. Here, in Part II, we present solar VUV observations over the last decades and their interpretations in terms of the plasma processes and the parameters of the solar atmosphere, with emphasis on the spatial and thermal structures of the chromosphere, transition region and corona of the quiet Sun. In addition, observations of active regions, solar flares and prominences are included as well as of small-scale events. Special sections are devoted to the elemental composition of the solar atmosphere and theoretical considerations on the heating of the corona and the generation of the solar wind.

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Section: Bright Pointsmentioning

confidence: 99%

Observations of the Sun at Vacuum-Ultraviolet Wavelengths from Space. Part II: Results and Interpretations

et al. 2007

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“…An MDI pixel is the smallest spatial scale which is accessible to us for the extrapolation and the assumption that each pixel supports a separate loop is driven by the small-scale structure seen by TRACE and the NIXT instrument (e.g. Golub et al 1990). Although individual plasma loops may well be formed from field lines gathered from different sized areas on the solar surface, our approach should in a statistic sense provide the correct distribution of loop lengths, heights, etc.…”

Section: Reconstruction Of the Magnetic Field In The Solar Atmospherementioning

confidence: 99%

Similarities and Differences between Coronal Holes and the Quiet Sun: Are Loop Statistics the Key?

Wiegelmann

Solanki

2004

Sol Phys

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Abstract. Coronal holes (CH) emit significantly less at coronal temperatures than quiet Sun regions (QS), but can hardly be distinguished in most chromospheric and lower transition region lines. A key quantity for the understanding of this phenomenon is the magnetic field. We use data from SOHO/MDI to reconstruct the magnetic field in coronal holes and the quiet Sun with the help of a potential magnetic model. Starting from a regular grid on the solar surface we then trace field lines, which provide the overall geometry of the 3D magnetic field structure.We distinguish between open and closed field lines, with the closed field lines being assumed to represent magnetic loops. We then try to compute some properties of coronal loops. The loops in the CH are found to be on average flatter than in the QS. High and long closed loops are extremely rare, whereas short and low-lying loops are almost as abundant in coronal holes as in the quiet Sun. When interpreted in the light of loop scaling laws this result suggests an explanation for the relatively strong chromospheric and transition region emission (many low-lying, short loops), but the weak coronal emission (few high and long loops) in coronal holes. In spite of this contrast our calculations also suggest that a significant fraction of the cool emission in CHs comes from the open flux regions. Despite these insights provided by the magnetic field line statistics further work is needed to obtain a definite answer to the question if loop statistics explain the differences between coronal holes and the quiet Sun.

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“…52 (9) area-weighted skewness and kurtosis measures of the data to estimate the non-Gaussian behavior of the dataset. All values shown are referred to as "initial measurement" values, which refer to the first reflectivity measurement taken in the mission timeline.…”

Section: Analysis and Discussionmentioning

confidence: 99%

“…52 (9) EUV passbands with the latter instruments, it differs in many ways (which we will not discuss herein but see Refs. 11 and 13 for more discussion on EIT and AIA, respectively), but the primary differences are that the mission and instrument designs of each telescope set them apart.…”

Section: Suvi Designmentioning

confidence: 99%

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Multisegmented, multilayer-coated mirrors for the Solar Ultraviolet Imager

et al. 2013

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Abstract. The Solar Ultraviolet Imager (SUVI) is one of the several instruments that will fly on board the next generation of Geostationary Operational Environmental Satellites R-U platforms, as part of the National Oceanic and Atmospheric Administration's space weather monitoring fleet. SUVI is a generalized Cassegrain telescope that employs multilayer-coated optics that operate in six extreme ultraviolet (EUV) narrow bandpasses centered at 93.9, 131.2, 171.1, 195.1, 284.2 and 303.8 Å. The innovation of the design is that SUVI is the first EUV solar telescope that has six different wavelength channels accommodated on each mirror. And despite having six segmented multilayer-coatings, shadowing (due to the mask) is minimized allowing SUVI to exceed its effective area specifications. Once operational, SUVI will record full-disk, spectroheliograms every few minutes, where this data will be used to better understand the effects of solar produced EUV radiation on Earth and the near-Earth environment. The material presented discusses general aspects of the SUVI optical design, mirror fabrication, super polishing, and metrology carried out to verify optical surface quality and in-band, EUV reflectivity performance of the multilayer coatings. The power spectral density and EUV measurements are shown to exceed performance requirements and are critical for the overall calibration and monitoring of SUVI's throughput and imaging performance, once operational.

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Sub-arcsecond observations of the solar X-ray corona

Cited by 160 publications

References 10 publications

Observations of the Sun at Vacuum-Ultraviolet Wavelengths from Space. Part II: Results and Interpretations

Observations of the Sun at Vacuum-Ultraviolet Wavelengths from Space. Part II: Results and Interpretations

Similarities and Differences between Coronal Holes and the Quiet Sun: Are Loop Statistics the Key?

Multisegmented, multilayer-coated mirrors for the Solar Ultraviolet Imager

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