Energetic (∼ 1 to 50 MeV) protons associated with Earth‐directed coronal mass ejections

Torsti, J.; Anttila, Anu-Hanna; Kocharov, L. G.; Mäkelä, P.; Riihonen, E.; Sahla, T.; Teittinen, M.; Валтонен, Э.; Laitinen, Timo; Vainio, Rami

doi:10.1029/98gl50062

Cited by 43 publications

(39 citation statements)

References 7 publications

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“…Furthermore, these authors assume that posteruptive soft X-ray arcades are the main candidate for coronal acceleration, antithetical to the CME bow shock acceleration in the interplanetary medium. It is surprising that we are listed among the authors who have suggested this, referring to Kocharov et al (1994) and Torsti et al (1996Torsti et al ( , 1998. The assumption that posteruptive arcades should produce significant SEP events even when the associated CMEs are too slow to drive shocks, was formulated and tested by Kahler et al (2000).…”

Section: Discussionmentioning

confidence: 99%

Injection of energetic protons during solar eruption on 1999 May 9: Effect of flare and coronal mass ejection

Torsti

Kocharov

Innes

et al. 2001

A&A

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Abstract. A solar energetic particle (SEP) event was observed on 1999 May 9 by the Energetic and Relativistic Nuclei and Electron instrument (ERNE) onboard the Solar and Heliospheric Observatory (SOHO) spacecraft in association with a coronal mass ejection (CME) and X-ray flare at the western limb. Near flare onset the active region coronal loop structure was seen to erupt and simultaneous blue and red shift velocities of the hot plasma were recorded by the SUMER (Solar Ultraviolet Measurements of Emitted Radiation) instrument onboard SOHO. We observe for the first time three periods of the SEP injection in a single event: (i) the first, extremely-hard spectrum injection triggered by the passage of the flare initiated coronal (shock) wave; (ii) a moderately-hard spectrum phase starting about half a hour later, proceeding and ceasing concurrently with metric continuum radio burst; (iii) a prolonged soft spectrum injection dominating in the late phase of the event, after about 1.5 h from the first proton production. The CME bow shock acceleration provides a straightforward explanation of the final spectral redressing, whereas the first acceleration seems triggered by the flare. These observations lead us to conclude that the 1999 May 9 SEP event was caused by a combination of coronal and interplanetary acceleration processes contributing with varying importance at different stages of the solar eruption associated with both flare and CME. Comparison with other events suggests that it is a common property of mixed SEP events.

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Section: Discussionmentioning

confidence: 99%

Injection of energetic protons during solar eruption on 1999 May 9: Effect of flare and coronal mass ejection

Torsti

Kocharov

Innes

et al. 2001

A&A

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“…They concluded that electrons and protons were promptly accelerated at a Moretonassociated shock. Calculated proton release times were found to be close to the times when EIT waves reached the western limb (Torsti et al, 1998(Torsti et al, , 1999. Along the same lines, a large sample of impulsive electron events was studied by Krucker et al (1999).…”

Section: Acceleration Of Solar Energetic Particles (Seps)mentioning

confidence: 99%

Large-scale Globally Propagating Coronal Waves

Warmuth

2015

Living Rev. Sol. Phys.

169

140

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Large-scale, globally propagating wave-like disturbances have been observed in the solar chromosphere and by inference in the corona since the 1960s. However, detailed analysis of these phenomena has only been conducted since the late 1990s. This was prompted by the availability of high-cadence coronal imaging data from numerous spaced-based instruments, which routinely show spectacular globally propagating bright fronts. Coronal waves, as these perturbations are usually referred to, have now been observed in a wide range of spectral channels, yielding a wealth of information. Many findings have supported the "classical" interpretation of the disturbances: fast-mode MHD waves or shocks that are propagating in the solar corona. However, observations that seemed inconsistent with this picture have stimulated the development of alternative models in which "pseudo waves" are generated by magnetic reconfiguration in the framework of an expanding coronal mass ejection. This has resulted in a vigorous debate on the physical nature of these disturbances. This review focuses on demonstrating how the numerous observational findings of the last one and a half decades can be used to constrain our models of large-scale coronal waves, and how a coherent physical understanding of these disturbances is finally emerging. Article RevisionsLiving Reviews supports two ways of keeping its articles up-to-date:Fast-track revision. A fast-track revision provides the author with the opportunity to add short notices of current research results, trends and developments, or important publications to the article. A fast-track revision is refereed by the responsible subject editor. If an article has undergone a fast-track revision, a summary of changes will be listed here.Major update. A major update will include substantial changes and additions and is subject to full external refereeing. It is published with a new publication number.For detailed documentation of an article's evolution, please refer to the history document of the article's online version at http://dx

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“…Almost all large proton events are associated with CMEs, but not all CMEs, however, produce high-energy (> 10 MeV) protons. Sometimes a CME of a higher transit speed produces much fewer protons than a slower CME originating from approximately the same solar longitude [Torsti et al, 1998a]. This adds complexity to both forecasting of the nearEarth proton flux and to our understanding of how a CME accelerates particles.…”

Section: Introductionmentioning

confidence: 99%

“…It is most likely that the observed protons were acclerated in vicinity of coronal Moreton wave and CME. Occurrence of the type II radio burst may be important as indication that a CME is likely to be productive in >10-MeV protons [Torsti et al, 1998a]. Ellison et al [1995] studied acceleration rates and injection efficiencies in oblique shocks.…”

Section: Comparison With Other Eventsmentioning

confidence: 99%

Energetic (∼10–65 MeV) protons observed by ERNE on August 13–14, 1996: Eruption on the solar back side as a possible source of the event

Torsti¹,

Kocharov²,

Teittinen³

et al. 1999

J. Geophys. Res.

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Abstract. The onset of the >10-MeV proton event of August 13-14, 1996, revealed a velocity dispersion, which is a signature of its solar origin, but no associated soft X ray flare was observed. The LASCO CME observations, the presence of AR 7981 beyond the west limb, and type II and IV radio burst timing with respect to the proton event onset indicate that the parent solar eruption may be centered on the back side of the Sun, at ---150øW. In such a case, expanding CME-associated wave can reach the Earth-connected interplanetary magnetic field line in ---1 hour and so give rise to the > 10-MeV proton event observed with the Energetic and Relativistic Nuclei and Electron (ERNE) instrument onboard SOHO. We verify this hypothesis against observational data and conclude that a solar back side eruption is the most plausible explanation of the August 13, 1996, event. We compare the August 13, 1996, event with events associated with Earth directed CMEs and show that the August 13, 1996, event reveals many properties common to >10-MeV proton events originating from solar eruptions centered ---90 ø away from the root of the Earth-connected interplanetary magnetic field line. In such events, the first detected protons are released ---1 hour after the start time of type II and IV radio bursts. The first injection spectrum is essentially harder than the spectrum at the intensity maximum; that is, the hard but less intensive proton production is followed by the major soft-spectrum production when CME expands farther from the Sun. sion that the interplanetary CME-driven shocks mainly accelerate seed particles originating from the solar corona. This may imply, when studying the efficiency of proton production, that more attention must be paid to the beginning of the event when the CME expands near the Sun.A careful study of the commencement of the August 13, 1996, particle event is important also because there were no signatures of a parent eruption in the GOES soft X ray data.

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Energetic (∼ 1 to 50 MeV) protons associated with Earth‐directed coronal mass ejections

Cited by 43 publications

References 7 publications

Injection of energetic protons during solar eruption on 1999 May 9: Effect of flare and coronal mass ejection

Injection of energetic protons during solar eruption on 1999 May 9: Effect of flare and coronal mass ejection

Large-scale Globally Propagating Coronal Waves

Energetic (∼10–65 MeV) protons observed by ERNE on August 13–14, 1996: Eruption on the solar back side as a possible source of the event

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