Solar Energetic Particle Event Associated With the 2012 July 23 Extreme Solar Storm

Zhu, Bei; Liu, Ying D.; Luhmann, J. G.; Hu, Huidong; Wang, Rui; Yang, Zhongwei

doi:10.3847/0004-637x/827/2/146

Cited by 12 publications

(11 citation statements)

References 72 publications

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“…The second reduction is probably owing to exclusion of the energetic particles by the strong magnetic field inside the ejecta (e.g., Liu et al 2008). The two-step decrease is similar to the behavior of the intensity of >10 MeV particles across the shock, sheath and the first ICME (Zhu et al 2016). This similarity may indicate that mainly the >10 MeV particles resulted in the CCD response for the current case.…”

Section: Complex Radio Type II Burstsupporting

confidence: 61%

“…Another detailed analysis of the in situ shock properties indicates a quasiparallel shock at STEREO A (Riley et al 2016), again supporting the "preconditioning" idea (Liu et al 2014). The longitudinal distribution of the solar energetic particle event associated with the CME is studied by Zhu et al (2016) using the particle data from STEREO and near-Earth spacecraft.…”

Section: Introductionmentioning

confidence: 56%

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Structure, Propagation, and Expansion of a Cme-Driven Shock in the Heliosphere: A Revisit of the 2012 July 23 Extreme Storm

Liu

Zhu

et al. 2017

ApJ

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We examine the structure, propagation and expansion of the shock associated with the 2012 July 23 extreme coronal mass ejection (CME). Characteristics of the shock determined from multi-point imaging observations are compared to in situ measurements at different locations and a complex radio type II burst, which according to our definition has multiple branches that may not all be fundamental-harmonic related. The white-light shock signature can be modeled reasonably well by a spherical structure and was expanding backward even on the opposite side of the Sun. The expansion of the shock, which was roughly self-similar after the first ∼1.5 hours from launch, largely dominated over the translation of the shock center for the time period of interest. Our study also suggests a bow-shock morphology around the nose at later times due to the outward motion in combination with the expansion of the ejecta. The shock decayed and failed to reach Mercury in the backward direction and STEREO B and Venus in the lateral directions, as indicated by the imaging and in situ observations. The shock in the nose direction, however, may persist to the far outer heliosphere, with predicted impact on Dawn around 06 UT on July 25 and on Jupiter around 23:30 UT on July 27 by an MHD model. The type II burst shows properties generally consistent with the spatial/temporal variations of the shock deduced from imaging and in situ observations. In particular, the lowfrequency bands agree well with the in situ measurements of a very low density ahead of the shock at STEREO A.

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Section: Complex Radio Type II Burstsupporting

confidence: 61%

Section: Introductionmentioning

confidence: 56%

Structure, Propagation, and Expansion of a Cme-Driven Shock in the Heliosphere: A Revisit of the 2012 July 23 Extreme Storm

Liu

Zhu

et al. 2017

ApJ

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“…We apply two methods to determine the release times of the first arriving particles observed at L1 and STEREO A, the velocity dispersion analysis (VDA; e.g., Huttunen-Heikinmaa et al 2005;Vainio et al 2013;Kouloumvakos et al 2015) and the time shifting analysis (TSA; e.g., Vainio et al 2013;Kouloumvakos et al 2016;Lario et al 2017b). The VDA is a typical method to determine the particle release time and the apparent path length, whose performance has been evaluated in several studies (e.g., Lintunen & Vainio 2004;Sáiz et al 2005;Rouillard et al 2012;Vainio et al 2013;Zhu et al 2016). The TSA method uses the onset time of the available highest energy channel of the particles and assumes that the first arriving particles observed by the spacecraft propagate scatter-freely along the nominal Parker spiral field lines.…”

Section: Calculation Of Particle Release Timesmentioning

confidence: 99%

Investigation of Energetic Particle Release Using Multi-point Imaging and In Situ Observations

Zhu

Liu

Kwon

et al. 2018

ApJ

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The solar eruption on 2012 January 27 resulted in a wide-spread solar energetic particle (SEP) event observed by STEREO A and the near-Earth spacecraft (separated by 108 • ). The event was accompanied by an X-class flare, extremeultraviolet (EUV) wave and fast coronal mass ejection (CME). We investigate the particle release by comparing the release times of particles at the spacecraft and the times when magnetic connectivity between the source and the spacecraft was established. The EUV wave propagating to the magnetic footpoint of the spacecraft in the lower corona and the shock expanding to the open field line connecting the spacecraft in the upper corona are thought to be responsible for the particle release. We track the evolution of the EUV wave and model the propagation of the shock using EUV and white-light observations. No obvious evidence indicates that the EUV wave reached the magnetic footpoint of either STEREO A or L1-observers. Our shock modeling shows that the release time of the particles observed at L1 was consistent with the time when the shock first established contact with the magnetic field line connecting L1-observers. The release of the particles observed by STEREO A was delayed relative to the time when the shock was initially connected to STEREO A via the magnetic field line. We suggest that the particle acceleration efficiency of the portion of the shock connected to the spacecraft determines the release of energetic particles at the spacecraft.

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“…The backside coronal mass ejection (CME) of 2012 July 23 has received considerable attention because many of its characteristics place it among historical extreme solar events (Baker et al 2013;Russell et al 2013;Ngwira et al 2013;Liu et al 2014;Liou et al 2014;Gopalswamy et al 2014a;Temmer and Nitta, 2015;Joyce et al 2015;Zhu et al 2016;Riley et al 2016, among others). For example, the shock transit time from the Sun to 1 au was ~18.5 hours, similar to the two 2003 Halloween events on October 28 and 29 and to 13 other fast-transit events since the Carrington event in 1859 (Gopalswamy et al 2005a;Cliver et al 1990a,b).…”

Section: Introductionmentioning

confidence: 99%

The 2012 July 23 Backside Eruption: An Extreme Energetic Particle Event?

Gopalswamy

Yashiro

Thakur

et al. 2016

ApJ

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The backside coronal mass ejection (CME) of 2012 July 23 had a short Sun to Earth shock transit time (18.5 hours). The associated solar energetic particle (SEP) event had a >10 MeV proton flux peaking at ~5000 pfu, and the energetic storm particle (ESP) event was an order of magnitude larger, making it the most intense event in the space era at these energies. By a detailed analysis of the CME, shock, and SEP characteristics, we find that the July 23 event is consistent with a high-energy SEP event (accelerating particles to GeV energies). The time of maximum and fluence spectra in the range 10-100 MeV were very hard, similar to those of ground level enhancement (GLE) events. We found a hierarchical relationship between the CME initial speeds and the fluence spectral indices: CMEs with low initial speeds had SEP events with the softest spectra, while those with highest initial speeds had SEP events with the hardest spectra. CMEs attaining intermediate speeds result in moderately hard spectra. The July 23 event was in the group of hard-spectrum events. During the July 23 event, the shock speed (>2000 km s -1 ), the initial acceleration (~1.70 km s -2 ), and the shock formation height (~1.5 solar radii) were all typical of GLE events. The associated type II burst had emission components from metric to kilometric wavelengths suggesting a strong shock. These observation confirm that the 2012 July 23 event is likely to be an extreme event in terms of the energetic particles it accelerated.

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Solar Energetic Particle Event Associated With the 2012 July 23 Extreme Solar Storm

Cited by 12 publications

References 72 publications

Structure, Propagation, and Expansion of a Cme-Driven Shock in the Heliosphere: A Revisit of the 2012 July 23 Extreme Storm

Structure, Propagation, and Expansion of a Cme-Driven Shock in the Heliosphere: A Revisit of the 2012 July 23 Extreme Storm

Investigation of Energetic Particle Release Using Multi-point Imaging and In Situ Observations

The 2012 July 23 Backside Eruption: An Extreme Energetic Particle Event?

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