Introduction to the physics of solar eruptions and their space weather impact

Archontis, V.; Vlahos, L.

doi:10.1098/rsta.2019.0152

Cited by 6 publications

(4 citation statements)

References 9 publications

(20 reference statements)

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“…The high energy emission recorded by the RHESSI satellite in the vicinity of jets confirms the presence of super hot plasmas, as we find it in our model. Also, the simultaneous detection of type III and HXR bursts during impulsive explosions, and the correlations with Solar Energetic Particles, are related with jets (Bain & Fletcher 2009;Glesener et al 2012;Glesener & Fleishman 2018;Chen et al 2013;Raouafi et al 2016;Archontis & Vlahos 2019), and can directly be understood in the frame of our model as resulting from the acceleration on sub-second time-scales in the fragmented environments near jets, when embedded in the global topology of emerging flux, as in Fig. 2 or 3.…”

Section: Discussionmentioning

confidence: 88%

Particle Acceleration and Heating in Regions of Magnetic Flux Emergence

Isliker

Archontis

Vlahos

2019

ApJ

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The interaction between emerging and pre-existing magnetic fields in the solar atmosphere can trigger several dynamic phenomena, such as eruptions and jets. A key element during this interaction is the formation of large scale current sheets and, eventually, their fragmentation that leads to the creation of a strongly turbulent environment. In this paper, we study the kinetic aspects of the interaction (reconnection) between emerging and ambient magnetic fields. We show that the statistical properties of the spontaneously fragmented and fractal electric fields are responsible for the efficient heating and acceleration of charged particles, which form a power law tail at high energies on sub-second time scales. A fraction of the energized particles escapes from the acceleration volume, with a super-hot component with temperature close to 150 MK, and with a power law high energy tail with index between -2 and -3. We estimate the transport coefficients in energy space from the dynamics of the charged particles inside the fragmented and fractal electric fields, and the solution of a fractional transport equation, as appropriate for a strongly turbulent plasma, agrees with the test particle simulations. We also show that the acceleration mechanism is not related to Fermi acceleration, and the Fokker Planck equation is inconsistent and not adequate as a transport model. Finally, we address the problem of correlations between spatial transport and transport in energy space. Our results confirm the observations reported for high energy particles (hard X-rays, type III bursts and solar energetic particles) during the emission of solar jets.

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Section: Discussionmentioning

confidence: 88%

Particle Acceleration and Heating in Regions of Magnetic Flux Emergence

Isliker

Archontis

Vlahos

2019

ApJ

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“…This paper is a review of the current status of predicting the space weather impact of CMEs and draws on our efforts within the Hellenic National Space Weather Research Network (HNSWR) 1 co-funded by the European Union and Greece [1]. To keep the paper focused and within a reasonable length, we discuss only certain CME impact parameters; namely, their time-ofarrival (ToA), speed-on-arrival (SoA), momentum, length of interaction with the magnetosphere (size), and their magnetic configuration expressed by the southward component, B z , of the CME-entrained magnetic field.…”

Section: Introductionmentioning

confidence: 99%

Predicting the geoeffective properties of coronal mass ejections: current status, open issues and path forward

Vourlidas

Patsourakos

Savani

2019

Phil. Trans. R. Soc. A.

109

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Much progress has been made in the study of coronal mass ejections (CMEs), the main drivers of terrestrial space weather thanks to the deployment of several missions in the last decade. The flow of energy required to power solar eruptions is beginning to be understood. The initiation of CMEs is routinely observed with cadences of tens of seconds with arc-second resolution. Their inner heliospheric evolution can now be imaged and followed routinely. Yet relatively little progress has been made in predicting the geoeffectiveness of a particular CME. Why is that? What are the issues holding back progress in medium-term forecasting of space weather? To answer these questions, we review, here, the measurements, status and open issues on the main CME geoeffective parameters; namely, their entrained magnetic field strength and configuration, their Earth arrival time and speed, and their mass (momentum). We offer strategies for improving the accuracy of the measurements and their forecasting in the near and mid-term future. To spark further discussion, we incorporate our suggestions into a top-level draft action plan that includes suggestions for sensor deployment, technology development and modelling/theory improvements. This article is part of the theme issue ‘Solar eruptions and their space weather impact’.

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“…Solar eruptions are complex phenomena with multiple facets right from their genesis in the solar atmosphere to subsequent consequences in the near-Sun, interplanetary, and near-Earth regions (Gopalswamy et al 2001;Webb & Howard 2012;Archontis & Vlahos 2019). Decades of observational and theoretical research has elucidated different aspects of it, namely, solar flares, eruptive prominences, coronal mass ejections (CMEs), coronal jets, etc., which are observationally defined as disjoint terms but occur as a result of physically coupled processes (e.g., see reviews by Priest & Forbes 2002;Fletcher et al 2011).…”

Section: Introductionmentioning

confidence: 99%

HXR emission from an activated flux rope and subsequent evolution of an eruptive long duration solar flare

Sahu,

Joshi,

Mitra

et al. 2020

Preprint

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In this paper, we present a comprehensive study of the evolutionary phases of a major M6.6 long duration event (LDE) with special emphasize on its pre-flare phase. The event occurred in NOAA 12371 on 2015 June 22. A remarkable aspect of the event was an active pre-flare phase lasting for about an hour during which a hot EUV coronal channel was in build-up stage and displayed co-spatial hard X-ray (HXR) emission up to energies of 25 keV. As such, this is the first evidence of HXR coronal channel. The coronal magnetic field configuration based on NLFFF modeling clearly exhibited a magnetic flux rope (MFR) oriented along the polarity inversion line (PIL) and co-spatial with the coronal channel. We observed significant changes in the AR's photospheric magnetic field during an extended period of ≈42 hours in the form of rotation of sunspots, moving magnetic features, and flux cancellation along the PIL. Prior to the flare onset, the MFR underwent a slow rise phase (≈14 km s −1 ) for ≈12 min which we attribute to the faster build-up and activation of the MFR by tethercutting reconnection occurring at multiple locations along the MFR itself. The sudden transition in the kinematic evolution of the MFR from the phase of slow to fast rise (≈109 km s −1 with acceleration ≈110 m s −2 ) precisely divides the pre-flare and impulsive phase of the flare, which points toward the feedback process between the early dynamics of the eruption and the strength of the flare magnetic reconnection.

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Introduction to the physics of solar eruptions and their space weather impact

Cited by 6 publications

References 9 publications

Particle Acceleration and Heating in Regions of Magnetic Flux Emergence

Particle Acceleration and Heating in Regions of Magnetic Flux Emergence

Predicting the geoeffective properties of coronal mass ejections: current status, open issues and path forward

HXR emission from an activated flux rope and subsequent evolution of an eruptive long duration solar flare

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