Variations in the relative elemental abundances of oxygen, neon, magnesium, and iron in high-temperature solar active-region and flare plasmas

McKenzie, D. L.; Feldman, U.

doi:10.1086/171249

Cited by 59 publications

(58 citation statements)

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“…The FIP bias in CHs is between 1 and 1.5 (Feldman et al 2005), while in ARs it can reach values larger than 4 in the case of older ARs (Widing & Feldman 2001). The remote measurements of the solar corona also show that the variation of FIP bias in ARs is larger than in CHs (McKenzie & Feldman 1992;Widing & Feldman 2001). Our results demonstrate that the N F e /N O ranges and their average value are higher in the AR wind.…”

Section: +mentioning

confidence: 99%

Charge States and FIP Bias of the Solar Wind from Coronal Holes, Active Regions, and Quiet Sun

Madjarska

Xia

et al. 2017

ApJ

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Connecting in-situ measured solar-wind plasma properties with typical regions on the Sun can provide an effective constraint and test to various solar wind models. We examine the statistical characteristics of the solar wind with an origin in different types of source regions. We find that the speed distribution of coronal hole (CH) wind is bimodal with the slow wind peaking at ∼400 km s −1 and a fast at ∼600 km s −1 . An anti-correlation between the solar wind speeds and the O 7+ /O 6+ ion ratio remains valid in all three types of solar wind as well during the three studied solar cycle activity phases, i.e. solar maximum, decline and minimum. The N F e /N O range and its average values all decrease with the increasing solar wind speed in different types of solar wind. The N F e /N O range (0.06-0.40, FIP bias range 1-7) for AR wind is wider than for CH wind (0.06-0.20, FIP bias range 1-3) while the minimum value of N F e /N O (∼ 0.06) does not change with the variation of speed, and it is similar for all source regions. The two-peak distribution of CH wind and the anti-correlation between the speed and O 7+ /O 6+ in all three types of solar wind can be explained qualitatively by both the waveturbulence-driven (WTD) and reconnection-loop-opening (RLO) models, whereas the distribution features of N F e /N O in different source regions of solar wind can be explained more reasonably by the RLO models.

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Section: +mentioning

confidence: 99%

Charge States and FIP Bias of the Solar Wind from Coronal Holes, Active Regions, and Quiet Sun

Madjarska

Xia

et al. 2017

ApJ

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“…All earlier measurements were done by X-ray instruments that were unable to image particular solar regions ; instead they collected radiation from the entire Sun. Using such an instrument, McKenzie & Feldman (1992) derived the elemental abundance in a large number of Ñares. According to them, Ñaring plasmas have FIP biases that vary between 1 and 4.…”

Section: Lines Suitable For Determining Elemental Abundances In High-mentioning

confidence: 99%

Identification of Spectral Lines in the 500–1600 A Wavelength Range of Highly Ionized Ne, Na, Mg, Ar, K, Ca, Ti, Cr, Mn, Fe, Co, and Ni Emitted by Flares (T_e≥ 3 x 10⁶K) and Their Potential Use in Plasma Diagnostics

Feldman

Curdt

Landi

et al. 2000

ApJ

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On 1999 May 9 the Solar Ultraviolet Measurements of Emitted Radiation (SUMER) spectrometer on the Solar and Heliospheric Observatory (SOHO) recorded spectra from a high-temperature region located in the solar corona above the west limb. These spectra contain lines from rather less-abundant elements in solar plasmas. In this paper we present identiÐcations of the high-temperature K) Ne, (T e º 3 ] 106 Na, Mg, Ar, K, Ca, Ti, Cr, Mn, Fe, Co, and Ni lines that were detected in the 500È1600 spectral range A of SUMER. In addition, accurate wavelength measurements have been obtained with uncertainties varying between 0.015 and 0.040(1 p). Making use of the newly measured wavelengths, we derive A energy levels in the ground conÐguration of a number of highly charged ions. We present intensity ratio calculations of lines in the SUMER range that could be used to measure electron densities in hightemperature solar plasmas. We also provide emissivities for Ca XIIIÈCa XV and Fe XVIIIÈFe XXIII lines that could be used to determine emission measures and electron temperatures of high-temperature plasmas. We discuss a method for measuring elemental abundance variations in high-temperature solar plasmas using lines presented in the paper. A list of spectral lines spanning the 300È30000 wavelength A range and their branching ratios that are suitable for efficiency calibration of space-borne spectrographs is provided.

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“…It might imply that the FIP fractionation as a whole tends to be slightly weaker in the average flare gas available to impulsive events than in the upper corona and slow solar wind gas sampled by the gradual events (which may well originate in specific narrow open-field structures squeezed between closed-loop systems at low altitude; Wang, Sheeley, & Nash 1990;Meyer 1993a, b). Alternatively, it might reflect a specific enhancement of Ne in flare gases with otherwise coronal composition, as found in gamma-ray and X-ray observations of some large impulsive flares (Murphy et al 1991;Murphy 1992;Schmelz & Fludra 1993;Schmelz 1993;Saba& Strong 1993;see also McKenzie &Feldman 1992 andMeyer 1993a, b). Shemi (1991) has tentatively interpreted these high Ne abundances in terms of an ion-neutral fractionation following a specific X-ray photoionization of Ne in a very dense medium (Meyer 1993a, b).…”

Section: Second-order Composition Anomaliesmentioning

confidence: 91%

“…Its abundance in the coronal gas is --' 5 times lower than those of NeMgSi, which might also influence its enhancement. Finally, S is an intermediate-FIP element (right at the borderline between those elements which are essentially ionized and those which are neutral in the region where the ion-neutral fractionation takes place), so that its behavior during ion-neutral fractionation taking place under slightly variable conditions cannot be easily predicted: it might possibly have an essentially photospheric abundance in the flare parent gas (e.g., Reames, Richardson, & Barbier 1991b;von Steiger et al 1992;McKenzie & Feldman 1992;Meyer 1993a, b).…”

Section: Second-order Composition Anomaliesmentioning

confidence: 99%

Energetic-Particle Abundances in Impulsive Solar Flare Events

Reames

Meyer²,

Rosenvinge³

1994

International Astronomical Union Colloquium

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We report on the abundances of energetic particles from impulsive solar flares, including those from a survey of 228 3 He-rich events, with 3 He/ 4 He > 0.1, observed by the ISEE 3 spacecraft from 1978 August through 1991 April. The rate of occurrence of these events corresponds to ~1000 events yr -1 on the solar disk at solar maximum. Thus the resonant plasma processes that enhance 3 He and heavy elements are a common occurrence in impulsive solar flares. To supply the observed fluence of 3 He in large events, the acceleration must be highly efficient and the source region must be relatively deep in the atmosphere at a density of more than 10 10 atoms cm" 3 . 3 He/ 4 He may decrease in very large impulsive events because of depletion of 3 He in the source region.The event-to-event variations in 3 He/ 4 He, H/ 4 He, e/p, and Fe/C are uncorrected in our event sample. Abundances of the elements show a pattern in which, relative to coronal composition, 4 He, C, N, and O have normal abundance ratios, while Ne, Mg, and Si are enhanced by a factor ~2.5 and Fe by a factor ~7 . This pattern suggests that elements are accelerated from a region of the corona with an electron temperature of ~3 -5 MK, where elements in the first group are fully ionized (Q/A = 0.5), those in the second group have two orbital electrons (Q/A ~ 0.43), and Fe has Q/A ~ 0.28. Ions with the same gyrofrequency absorb waves of that frequency and are similarly accelerated and enhanced. Further stripping may occur after acceleration as the ions begin to interact with the streaming electrons that generated the plasma waves.

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Variations in the relative elemental abundances of oxygen, neon, magnesium, and iron in high-temperature solar active-region and flare plasmas

Cited by 59 publications

References 0 publications

Charge States and FIP Bias of the Solar Wind from Coronal Holes, Active Regions, and Quiet Sun

Charge States and FIP Bias of the Solar Wind from Coronal Holes, Active Regions, and Quiet Sun

Identification of Spectral Lines in the 500–1600 A Wavelength Range of Highly Ionized Ne, Na, Mg, Ar, K, Ca, Ti, Cr, Mn, Fe, Co, and Ni Emitted by Flares (T_e≥ 3 x 10⁶K) and Their Potential Use in Plasma Diagnostics

Energetic-Particle Abundances in Impulsive Solar Flare Events

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Variations in the relative elemental abundances of oxygen, neon, magnesium, and iron in high-temperature solar active-region and flare plasmas

Cited by 59 publications

References 0 publications

Charge States and FIP Bias of the Solar Wind from Coronal Holes, Active Regions, and Quiet Sun

Charge States and FIP Bias of the Solar Wind from Coronal Holes, Active Regions, and Quiet Sun

Identification of Spectral Lines in the 500–1600 A Wavelength Range of Highly Ionized Ne, Na, Mg, Ar, K, Ca, Ti, Cr, Mn, Fe, Co, and Ni Emitted by Flares (Te≥ 3 x 106K) and Their Potential Use in Plasma Diagnostics

Energetic-Particle Abundances in Impulsive Solar Flare Events

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Identification of Spectral Lines in the 500–1600 A Wavelength Range of Highly Ionized Ne, Na, Mg, Ar, K, Ca, Ti, Cr, Mn, Fe, Co, and Ni Emitted by Flares (T_e≥ 3 x 10⁶K) and Their Potential Use in Plasma Diagnostics