Deriving the Properties of Coronal Pressure Fronts in 3d: Application to the 2012 May 17 Ground Level Enhancement

Rouillard, A. P.; Plotnikov, Illya; Pinto, Rui; Tirole, M.; Lavarra, M.; Zucca, Pietro; Vainio, R.; Tylka, A. J.; Vourlidas, A.; Rosa, M. L. De; Linker, J. A.; Warmuth, A.; Mann, G.; Cohen, C. M. S.; Mewaldt, R. A.

doi:10.3847/1538-4357/833/1/45

Cited by 105 publications

(179 citation statements)

References 84 publications

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“…Here, there is a significant difference with the previous OCBF, in that a large patch of high-u BN values close to the flanks of the OCBF develops over time, including many open field line crossings. Similar patches, or 'valleys' of quasi-perpendicularity were previously discussed by Kozarev et al (2015) and Rouillard et al (2016), and could mean that efficient particle acceleration may take place along a long linear structure on the shock surface. The nominal connectivity to Earth throughout the event is very good, and increases, as well as the spread of connected field lines (panels G and H).…”

Section: December 12 2013 Eventmentioning

confidence: 75%

The Coronal Analysis of SHocks and Waves (CASHeW) framework

Kozarev

Davey

Kendrick

et al. 2017

J. Space Weather Space Clim.

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-Coronal bright fronts (CBF) are large-scale wavelike disturbances in the solar corona, related to solar eruptions. They are observed (mostly in extreme ultraviolet (EUV) light) as transient bright fronts of finite width, propagating away from the eruption source location. Recent studies of individual solar eruptive events have used EUVobservations of CBFs and metric radio type II burst observations to show the intimate connection between waves in the low corona and coronal mass ejection (CME)-driven shocks. EUV imaging with the atmospheric imaging assembly instrument on the solar dynamics observatory has proven particularly useful for detecting large-scale short-lived CBFs, which, combined with radio and in situ observations, holds great promise for early CME-driven shock characterization capability. This characterization can further be automated, and related to models of particle acceleration to produce estimates of particle fluxes in the corona and in the near Earth environment early in events. We present a framework for the coronal analysis of shocks and waves (CASHeW). It combines analysis of NASA Heliophysics System Observatory data products and relevant data-driven models, into an automated system for the characterization of off-limb coronal waves and shocks and the evaluation of their capability to accelerate solar energetic particles (SEPs). The system utilizes EUV observations and models written in the interactive data language. In addition, it leverages analysis tools from the SolarSoft package of libraries, as well as third party libraries. We have tested the CASHeW framework on a representative list of coronal bright front events. Here we present its features, as well as initial results. With this framework, we hope to contribute to the overall understanding of coronal shock waves, their importance for energetic particle acceleration, as well as to the better ability to forecast SEP events fluxes.

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Section: December 12 2013 Eventmentioning

confidence: 75%

The Coronal Analysis of SHocks and Waves (CASHeW) framework

Kozarev

Davey

Kendrick

et al. 2017

J. Space Weather Space Clim.

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“…It has been shown that in the 2012 May 17 GLE event, the first in solar cycle 24, the CME shock originated below a streamer and the streamer magnetic configuration strongly affects the obliquity of the shock as it moves outward (Rouillard et al 2016). To better understand the physical connection between large SEP events and CME/shock-streamer interactions, the large-scale magnetic configuration in the CME shock initiation region should be examined for more events.…”

Section: Conclusion and Discussionmentioning

confidence: 99%

“…Recently, Rouillard et al (2016) showed that the CME shock of the GLE event on 2012 May 17 originated below a streamer, indicating that the large-scale magnetic configuration of streamers may also affect SEP acceleration at coronal shocks. However, due to the limited capability of current imaging observations of CME -streamer interaction in the corona, and the unavailability of direct measurement of coronal magnetic field topology, the role of streamers or CME-streamer interaction in the acceleration, trapping, and release of energetic particles remains unclear (see, e.g., Kahler et al 2000;Kahler & Vourlidas 2005;Rouillard et al 2016;Kocharov et al 2017).…”

Section: Introductionmentioning

confidence: 99%

“…However, due to the limited capability of current imaging observations of CME -streamer interaction in the corona, and the unavailability of direct measurement of coronal magnetic field topology, the role of streamers or CME-streamer interaction in the acceleration, trapping, and release of energetic particles remains unclear (see, e.g., Kahler et al 2000;Kahler & Vourlidas 2005;Rouillard et al 2016;Kocharov et al 2017). Here, we present a numerical model to investigate particle acceleration at shocks close to the Sun, with a focus on the possible role of large-scale streamer-like magnetic configuration in producing large SEP events.…”

Section: Introductionmentioning

confidence: 99%

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The Acceleration of High-energy Protons at Coronal Shocks: The Effect of Large-scale Streamer-like Magnetic Field Structures

Kong

Guo

Giacalone

et al. 2017

ApJ

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Recent observations have shown that coronal shocks driven by coronal mass ejections can develop and accelerate particles within several solar radii in large solar energetic particle (SEP) events. Motivated by this, we present an SEP acceleration study that including the process in which a fast shock propagates through a streamer-like magnetic field with both closed and open field lines in the low corona region. The acceleration of protons is modeled by numerically solving the Parker transport equation with spatial diffusion both along and across the magnetic field. We show that particles can be sufficiently accelerated to up to several hundred MeV within 2-3 solar radii. When the shock propagates through a streamer-like magnetic field, particles are more efficiently accelerated compared to the case with a simple radial magnetic field, mainly due to perpendicular shock geometry and the natural trapping effect of closed magnetic fields. Our results suggest that the coronal magnetic field configuration is an important factor for producing large SEP events. We further show that the coronal magnetic field configuration strongly influences the distribution of energetic particles, leading to different locations of source regions along the shock front where most high-energy particles are concentrated. This work may have strong implications for SEP observations. The upcoming Parker Solar Probe will provide in situ observations for the distribution of energetic particles in the coronal shock region, and test the results of the study.

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“…There is a growing amount of evidence for the association of CME-driven shocks with SEPs in the corona (see recent papers, e.g., Rouillard et al, 2012Rouillard et al, , 2016Carley et al, 2013;Lario et al, 2014Lario et al, , 2016Salas-Matamoros et al, 2016, and references therein) but it remains unclear whether such shock waves are capable of accelerating particles at the observed energies Mancuso, 2010, 2011). An important shock parameter that could be accessible from coronagraphic observations is the ratio between the downstream and upstream electron densities or density compression ratio, X.…”

Section: Introductionmentioning

confidence: 99%

The density compression ratio of shock fronts associated with coronal mass ejections

Kwon

Vourlidas

2018

J. Space Weather Space Clim.

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-We present a new method to extract the three-dimensional electron density profile and density compression ratio of shock fronts associated with coronal mass ejections (CMEs) observed in white light coronagraph images. We demonstrate the method with two examples of fast halo CMEs (∼2000 km s À1 ) observed on 2011 March 7 and 2014 February 25. Our method uses the ellipsoid model to derive the threedimensional geometry and kinematics of the fronts. The density profiles of the sheaths are modeled with double-Gaussian functions with four free parameters, and the electrons are distributed within thin shells behind the front. The modeled densities are integrated along the lines of sight to be compared with the observed brightness in COR2-A, and a x 2 approach is used to obtain the optimal parameters for the Gaussian profiles. The upstream densities are obtained from both the inversion of the brightness in a pre-event image and an empirical model. Then the density ratio and Alfvénic Mach number are derived. We find that the density compression peaks around the CME nose, and decreases at larger position angles. The behavior is consistent with a driven shock at the nose and a freely propagating shock wave at the CME flanks. Interestingly, we find that the supercritical region extends over a large area of the shock and lasts longer (several tens of minutes) than past reports. It follows that CME shocks are capable of accelerating energetic particles in the corona over extended spatial and temporal scales and are likely responsible for the wide longitudinal distribution of these particles in the inner heliosphere. Our results also demonstrate the power of multi-viewpoint coronagraphic observations and forward modeling in remotely deriving key shock properties in an otherwise inaccessible regime.

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Deriving the Properties of Coronal Pressure Fronts in 3d: Application to the 2012 May 17 Ground Level Enhancement

Cited by 105 publications

References 84 publications

The Coronal Analysis of SHocks and Waves (CASHeW) framework

The Coronal Analysis of SHocks and Waves (CASHeW) framework

The Acceleration of High-energy Protons at Coronal Shocks: The Effect of Large-scale Streamer-like Magnetic Field Structures

The density compression ratio of shock fronts associated with coronal mass ejections

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