Energetic-particle abundances in impulsive solar flare events

Reames, D. V.; Meyer, J. P.; Rosenvinge, T. T. von

doi:10.1086/191887

Cited by 252 publications

(205 citation statements)

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“…The plateau in the Fe/O curve seen on the right side of Figures 3È5, and to some extent in the 22Ne/20Ne and Fe/Mg curves in Figure 6, is consistent with the earlier results of Mason et al (1986) and Reames et al (1994), who found no correlation with Fe enrichments and 3He/4He for 3He/4He [ 0.1. It appears that for the impulsive events, the 3He/4He can change by orders of magnitude without a corresponding change in the other abundances.…”

Section: Observationssupporting

confidence: 91%

“…For impulsive events, associated with Ñares, the average abundances also show a trend in Q/A, with smaller Q/A values having larger enhancements, but they do not typically follow a power law. Furthermore, for some SEP events, the 3He/4He ratio is observed to be enhanced by as much as a factor of 104 compared with the solar wind values of 4.8 ] 10~4 (Ogilvie et al 1980 ;Hsieh & Simpson 1970 ;Reames, von Rosenvinge, & Lin 1985 ;Reames, Meyer, & von Rosenvinge 1994 ;Mason, Dwyer, & Mazur 2000). The enhancement of 3He does not follow the same pattern as the heavier elements, since the Q/A for 3He and 4He would predict a 3He depletion, rather than an enhancement.…”

Section: Introductionmentioning

confidence: 86%

“…(The cuto † of the data at 3He/4He D 0.001 is an instrumental e †ect.) Note that the good correlation seen over the entire 3He/4He range appears substantially weaker when limiting the data to 3He/4He [ 0.1, the range used by Mason et al (1986) and Reames et al (1994) when they reported seeing no correlation between Fe/O and 3He/4He. Presumably, the low 3He/4He data correspond to gradual, CME-associated events, and the high 3He/4He data correspond to impulsive, Ñare-associated events.…”

Section: Observationsmentioning

confidence: 97%

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Isotopic Composition of Solar Energetic Particle Events Measured byAdvanced Composition Explorer/ULEIS

Dwyer

Mason

Mazur

et al. 2001

ApJ

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Since its 1997 August launch, the Ultra Low Energy Isotope Spectrometer (ULEIS) on board the Advanced Composition Explorer (ACE) has observed a large number of solar energetic particle (SEP) events in the 0.4È3 MeV nucleon~1 range. These events show remarkable variability of both the elemental and isotopic compositions, with 22Ne/20Ne varying, from event to event, by up to a factor of 10, Fe/O by up to a factor of 100, and 3He/4He by up to a factor of 104. In this paper we present new measurements of the 22Ne/20Ne, 26Mg/24Mg, and 3He/4He ratios at D1 MeV nucleon~1 and compare these ratios to the iron abundances measured during the same time periods. We Ðnd that the elemental abundances, Fe/O and Fe/Mg, and the isotopic abundances, 22Ne/20Ne and 26Mg/24Mg, are all well ordered by both the 3He/4He ratio and the average Fe charge state as measured by ACE/SEPICA. These variations in 22Ne/20Ne and 26Mg/24Mg are much larger than expected from the charge to mass dependence derived for the elemental abundances, and we suggest that the large Ñuctuations seen for the neon and magnesium isotopes are related to the amount of impulsive Ñare material present.

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Section: Observationssupporting

confidence: 91%

Section: Introductionmentioning

confidence: 86%

Section: Observationsmentioning

confidence: 97%

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Isotopic Composition of Solar Energetic Particle Events Measured byAdvanced Composition Explorer/ULEIS

Dwyer

Mason

Mazur

et al. 2001

ApJ

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“…When electron acceleration ceases, the 3 He/ 4 He ratio is frozen and no further ion acceleration occurs. The time-integrated total number of 3 He nuclei being accelerated above 1.3 MeV amu À1 in an impulsive flare is about 10 31 particles (Reames et al 1994). Assuming the flaring area to be of about 10 17 cm 2 with a scale height of 10 9 cm, the proton density n H ¼ 5 Â 10 10 cm À3 , and 3 He=H ¼ 5 Â 10 À5 , there are 2:5 Â 10 32 3 He ions available in the flaring volume.…”

Section: Abundance Enhancementsmentioning

confidence: 99%

“…3. A time-integrated total of about 10 31 3 He nuclei is required to account for the observed particle fluxes (Reames, Meyer, & von Rosenvinge 1994).…”

Section: No 1 2003mentioning

confidence: 99%

Acceleration and Enrichment of³He in Impulsive Solar Flares by Electron Firehose Waves

Paesold

Kallenbach

Benz

2003

ApJ

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A new mechanism for acceleration and enrichment of 3 He during impulsive solar flares is presented. Lowfrequency electromagnetic plasma waves excited by the electron firehose instability (EFI) can account for the acceleration of ions up to 1 MeV amu À1 energies as a single-stage process. The EFI arises as a direct consequence of the free energy stored in a temperature anisotropy (T e k > T e ? ) of the bulk energized electron population during the acceleration process. In contrast to other mechanisms that require special plasma properties, the EFI is an intrinsic feature of the acceleration process of the bulk electrons. Being present as a side effect in the flaring plasma, these waves can account for the acceleration of 3 He and 4 He while selectively enhancing 3 He as a result of the spectral energy density built up from linear growth. Linearized kinetic theory, analytic models, and test particle simulations have been applied to investigate the ability of the waves to accelerate and fractionate. As waves grow in both directions parallel to the magnetic field, they can trap resonant ions and efficiently accelerate them to the highest energies. Plausible models have been found that can explain the observed energies, spectra, and abundances of 3 He and 4 He.

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MMS observation of inverse energy dispersion in shock drift accelerated ions

et al. 2017

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The four Magnetospheric Multiscale (MMS) spacecraft observed a ∼1 min burst of energetic ions (50–1000 keV) in the region upstream from the subsolar quasi‐perpendicular bow shock on 6 December 2015. The composition, flux levels, and spectral indices of these energetic protons, helium, and oxygen ions greatly resemble those seen in the outer magnetosphere earlier while MMS crossed the magnetopause and differ significantly from those simultaneously observed far upstream by Advanced Composition Explorer (ACE). However, the event cannot be explained solely in terms of leakage from the magnetosphere. The strongly southward orientation of the interplanetary magnetic field (IMF) lines at the time of the event precludes any connection to the magnetosphere. This point is confirmed by the presence of energetic electrons, known to occur on magnetic field lines that graze the bow shock rather than connect to the magnetosphere. We suggest that the ions gradient drifted out of the nearby quasi‐parallel foreshock and into the quasi‐perpendicular bow shock. Each of the ion species exhibited an inverse energy dispersion. As predicted by models for shock drift acceleration, the energies of the ions increased as θBn, the angle between the IMF and the shock normal, increased. Finally, we note that a similar event was observed a few minutes later in the subsolar magnetosheath, indicating that such events can be swept downstream of the bow shock.

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Energetic-particle abundances in impulsive solar flare events

Cited by 252 publications

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Isotopic Composition of Solar Energetic Particle Events Measured byAdvanced Composition Explorer/ULEIS

Isotopic Composition of Solar Energetic Particle Events Measured byAdvanced Composition Explorer/ULEIS

Acceleration and Enrichment of³He in Impulsive Solar Flares by Electron Firehose Waves

MMS observation of inverse energy dispersion in shock drift accelerated ions

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Energetic-particle abundances in impulsive solar flare events

Cited by 252 publications

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Isotopic Composition of Solar Energetic Particle Events Measured byAdvanced Composition Explorer/ULEIS

Isotopic Composition of Solar Energetic Particle Events Measured byAdvanced Composition Explorer/ULEIS

Acceleration and Enrichment of3He in Impulsive Solar Flares by Electron Firehose Waves

MMS observation of inverse energy dispersion in shock drift accelerated ions

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Acceleration and Enrichment of³He in Impulsive Solar Flares by Electron Firehose Waves