Accelerated Particle Composition and Energetics and Ambient Abundances from Gamma‐Ray Spectroscopy of the 1991 June 4 Solar Flare

Murphy, R. J.; Share, G. H.; Grove, J. E.; Johnson, W. N.; Kinzer, R. L.; Kurfess, J. D.; Strickman, M. S.; Jung, G. V.

doi:10.1086/304902

Cited by 81 publications

(68 citation statements)

References 51 publications

(60 reference statements)

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“…For the 9 June flare no signal from pion decay could be detected by COMPTEL at any time. Consistent with these results, Murphy et al (1997) found a comparable decay profile consisting of two different exponential decline constants for the 4 June 1991 flare from OSSE data.…”

Section: Discussionsupporting

confidence: 76%

Extended gamma-ray emission of the solar flares in june 1991

Rank

Ryan

Debrunner

et al. 2001

A&A

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Abstract. During the solar flares on 9, 11, and 15 June 1991 the COMPTEL instrument measured extended γ-radiation in the 2.223 MeV neutron-capture line, in prompt nuclear deexcitation lines and in pion-decay radiation for several hours after the flares. The long-term time profiles can be described by a double exponential decay with decay constants on the order of 10 min for the fast and several 100 min for the slow components. We studied the 11 June 1991 flare in more detail and found that during the extended phase the accelerated proton and ion spectrum is harder, the e/p ratio is lower, and the emission profile is smoother, compared to those of the impulsive phase. Pion-decay radiation was not detected before the onset of the extended emission phase. When comparing the three flares to one another, we found a striking similarity in the time profiles of the nuclear line and the neutron capture line emission. However, the pion-decay radiation varied in intensity significantly from flare to flare. The impulsive-phase emissions of the flares show no such similarity. Our measurements indicate that the processes taking place during the extended phase differ from those during the impulsive phase, or in other γ-ray line flares. Based on these results long-term trapping of energetic particles from the impulsive phase seems unlikely, as opposed to continuous particle acceleration.

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Section: Discussionsupporting

confidence: 76%

Extended gamma-ray emission of the solar flares in june 1991

Rank

Ryan

Debrunner

et al. 2001

A&A

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“…With a more complete treatment of the Comptel neutron response, Toner et al (2001) found a smaller value for the total number of produced neutrons, thus implying an even more pronounced steepening around 300 MeV than that deduced by Kocharov et al Flare-integrated ion numbers found in this paper from the nuclear line fluence are in the region of N p>30 MeV ∼ 4 × 10 33 (spectra 1 to 4 with δ = 3) in agreement with the lower limit deduced from the 2.2 MeV line in Debrunner et al (1997), but a factor of two lower than the number deduced from the neutrons in the same paper. We note that an abundance enhancement of accelerated α's, from α/p = 0.1 to 0.5, suggested in other events from studies of Li and Be formation lines (Share & Murphy 1998), would at least double the neutron yield (Murphy et al 1997;Hua et al 2002) potentially resolving any discrepancy.…”

Section: Discussionmentioning

confidence: 53%

High energy particles accelerated during the large solar flare of 1990 May 24: X/γ-ray observations

Vilmer

MacKinnon

Trottet

et al. 2003

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Abstract. The PHEBUS experiment aboard GRANAT observed γ-ray line emission and γ-ray continuum above 10 MeV from the 24 May, 1990 solar flare. Observations and interpretation of the high-energy continuum have been discussed previously. Here we re-examine these, combining the PHEBUS observations above 10 MeV with calculations of the pion decay continuum to quantitatively constrain the accelerated ion energy distribution at energies above 300 MeV. The uncertainty in the determination of the level of the primary electron bremsstrahlung as well as the lack of measurements on the γ-ray emission above 100 MeV combine to allow rather a wide range of energy distribution parameters (in terms of the number of protons above 30 MeV, the spectral index of the proton distribution and the high energy cut-off of the energetic protons). Nevertheless we are able to rule out some combinations of these parameters. Using the additional information provided by the γ-ray line observations we discuss whether it is possible to construct a consistent picture of the ions which are accelerated in a wide energy range during this flare. Our findings are discussed with respect to previous works on the spectrum of energetic protons in the 10 MeV to GeV energy range.

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“…Early work on the modelling of pion decay radiation and -ray emission (produced by >10 MeV ions) (Murphy et al 1997) gave a first determination of the high energy spectrum of ions in flares. Assuming a spectral shape for the energetic ions (either a Bessel function or a power law), number and spectra of energetic protons were estimated for both the impulsive and the extended phase of the first detected event (1980 Jun 21) and showed that the proton spectrum was steeper in the impulsive phase than in the later, so-called 'extended' phase.…”

Section: Pion-decay -Ray Emissionmentioning

confidence: 99%