An emerging flux model for the solar flare phenomenon

Heyvaerts, J.; Priest, E. R.; Rust, David M.

doi:10.1086/155453

Cited by 659 publications

(316 citation statements)

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“…Flux emergence is the driver in the model of Heyvaerts et al (1977), where we can distinguish three phases: (1) new magnetic flux emerges and a current sheet forms between the old and the new flux; (2) the current sheet loses equilibrium at a critical height and turbulent resistivity causes particles acceleration and triggers chromospheric evaporation; (3) the current sheet reaches a new steady state with marginal reconnection. A requirement of this model is the pre-existence of a stable current sheet for a day or more.…”

Section: Scientific Models For Solar Flaresmentioning

confidence: 99%

Solar Weather Event Modelling and Prediction

et al. 2009

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Key drivers of solar weather and mid-term solar weather are reviewed by considering a selection of relevant physics-and statistics-based scientific models as well as a selection of related prediction models, in order to provide an updated operational scenario for space weather applications. The characteristics and outcomes of the considered scientific and prediction models indicate that they only partially cope with the complex nature of solar activity for the lack of a detailed knowledge of the underlying physics. This is indicated by the fact that, on one hand, scientific models based on chaos theory and non-linear dynamics reproduce better the observed features, and, on the other hand, that prediction models based on statistics and artificial neural networks perform better. To date, the solar weather prediction success at most time and spatial scales is far from being satisfactory, but the forthcoming ground-and space-based high-resolution observations can add fundamental tiles to the modelling and predicting frameworks as well as the application of advanced mathematical approaches in the analysis of diachronic solar observations, that are a must to provide comprehensive and homogeneous data sets.

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Section: Scientific Models For Solar Flaresmentioning

confidence: 99%

Solar Weather Event Modelling and Prediction

et al. 2009

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“…The way of reconnection, however, depends largely on the magnetic configuration. In the two-dimensional (2D) case, new magnetic fluxes emerge from beneath the photosphere and reconnect with the pre-existing, open magnetic fields of opposite polarity, resulting in hot, collimated jets and two bright lobes at the base of jets (Heyvaerts et al, 1977;Shibata et al, 1992;Yokoyama & Shibata, 1996). Such mechanism became popular and was developed in the state-of-the-art, three-dimension (3D) magnetohydrodynamic (MHD) numerical experiments (Moreno-Insertis et al, 2008;Moreno-Insertis & Galsgaard, 2013;Archontis & Hood, 2013;Fang et al, 2014).…”

Section: Introductionmentioning

confidence: 99%

Observations of Multiple Blobs in Homologous Solar Coronal Jets in Closed Loop

Zhang

2016

Sol Phys

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Coronal bright points (CBPs) and jets are ubiquitous small-scale brightenings that are often associated with each other. In this paper, we report our multiwavelength observations of two groups of homologous jets. The first group was observed by the Extreme-Ultraviolet Imager (EUVI) aboard the behind Solar TErrestrial RElations Observatory (STEREO) spacecraft in 171Å and 304Å on 2014 September 10, from a location where data from the Solar Dynamic Observatory (SDO) could not observe. The jets (J1−J6) recurred for six times with intervals of 5−15 minutes. They originated from the same primary CBP (BP1) and propagated in the northeast direction along large-scale, closed coronal loops. Two of the jets (J3 and J6) produced sympathetic CBPs (BP2 and BP3) after reaching the remote footpoints of the loops. The time delays between the peak times of BP1 and BP2 (BP3) are 240±75 s (300±75 s). The jets were not coherent. Instead, they were composed of bright and compact blobs. The sizes and apparent velocities of the blobs are 4.5−9 Mm and 140−380 km s −1 , respectively. The arrival times of the multiple blobs in the jets at the far-end of the loops indicate that the sympathetic CBPs are caused by jet flows rather than thermal conduction fronts. The second group was observed by the Atmospheric Imaging Assembly aboard SDO in various wavelengths on 2010 August 3. Similar to the first group, the jets originated from a short-lived bright point (BP) at the boundary of active region 11092 and propagated along a small-scale, closed loop before flowing into the active region. Several tiny blobs with sizes of ∼1.7 Mm and apparent velocity of ∼238 km s −1 were identified in the jets. We carried out the differential emission measure (DEM) inversions to investigate the temperatures of the blobs, finding that the blobs were multithermal with average temperature of 1.8−3.1 MK. The estimated number densities of the blobs were (1.7−2.8)×10 9 cm −3 .

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“…The core field is directed nearly parallel to the neutral line whereas in the potential-field configuration it would be nearly orthogonal to the neutral line. This signifies that the core field is so greatly deformed from the potential field that most of its magnetic energy is free energy (e.g., Svestka 1976; Heyvaerts et al 1977;Sturrock 1980;Zirin 1988;Moore 1988;Moore and Sterling 2006). This pent-up free energy renders the core field or even the entire arcade capable of erupting.…”

Section: Isolated-arcade Eruptionsmentioning

confidence: 99%

Observed Aspects of Reconnection in Solar Eruptions

et al. 2011

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The observed magnetic field configuration and signatures of reconnection in the large solar magnetic eruptions that make major flares and coronal mass ejections and in the much smaller magnetic eruptions that make X-ray jets are illustrated with cartoons and representative observed eruptions. The main reconnection signatures considered are the imaged bright emission from the heated plasma on reconnected field lines. In any of these eruptions, large or small, the magnetic field that drives the eruption and/or that drives the buildup to the eruption is initially a closed bipolar arcade. From the form and configuration of the magnetic field in and around the driving arcade and from the development of the reconnection signatures in coordination with the eruption, we infer that (1) at the onset of reconnection the reconnection current sheet is small compared to the driving arcade, and (2) the current sheet can grow to the size of the driving arcade only after reconnection starts and the unleashed erupting field dynamically forces the current sheet to grow much larger, building it up faster than the reconnection can tear it down. We conjecture that the fundamental reason the quasi-static pre-eruption field is prohibited from having a large current sheet is that the magnetic pressure is much greater than the plasma pressure in the chromosphere and low corona in eruptive solar magnetic fields.

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An emerging flux model for the solar flare phenomenon

Cited by 659 publications

References 0 publications

Solar Weather Event Modelling and Prediction

Solar Weather Event Modelling and Prediction

Observations of Multiple Blobs in Homologous Solar Coronal Jets in Closed Loop

Observed Aspects of Reconnection in Solar Eruptions

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