Does Nearby Open Flux Affect the Eruptivity of Solar Active Regions?

DeRosa, Marc L.; Barnes, G.

doi:10.3847/1538-4357/aac77a

Cited by 16 publications

(9 citation statements)

References 59 publications

(52 reference statements)

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“…Observations and numerical modeling of flaring ARs show that, for the failed events, a magnetic flux rope is often trapped in the AR core and does not have an access to open fields (Toriumi et al. 2017b ; Toriumi and Takasao 2017 ; DeRosa and Barnes 2018 ). As the Zeeman Doppler Imaging by Morin et al.…”

Section: Discussionmentioning

confidence: 99%

“…The same mechanism explains the observed result by Toriumi et al (2017b) that the ratio of reconnected flux (in the flare ribbons) to the total AR flux is, on average, smaller for failed events than eruptive cases. DeRosa and Barnes (2018) showed that X-class flares located near coronal fields that are open to the heliosphere are eruptive at a higher rate than those lacking access to open fields.…”

Section: Solar Flares and Cmesmentioning

confidence: 99%

“…2.2 and 4.1.5, the flare eruption tends to fail when the overlying coronal loops are strong and slowly decaying over height (Wang et al 2017a;Vasantharaju et al 2018;Jing et al 2018). Observations and numerical modeling of flaring ARs show that, for the failed events, a magnetic flux rope is often trapped in the AR core and does not have an access to open fields (Toriumi et al 2017b;Toriumi and Takasao 2017;DeRosa and Barnes 2018). As the Zeeman Doppler Imaging by Morin et al (2008) suggests, active M dwarfs tend to be covered by strong magnetic patches over the entire stellar surface.…”

Section: Connection With Stellar Flares and Cmesmentioning

confidence: 99%

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Flare-productive active regions

Toriumi

Wang

2019

Living Rev Sol Phys

235

151

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Strong solar flares and coronal mass ejections, here defined not only as the bursts of electromagnetic radiation but as the entire process in which magnetic energy is released through magnetic reconnection and plasma instability, emanate from active regions (ARs) in which high magnetic non-potentiality resides in a wide variety of forms. This review focuses on the formation and evolution of flare-productive ARs from both observational and theoretical points of view. Starting from a general introduction of the genesis of ARs and solar flares, we give an overview of the key observational features during the long-term evolution in the pre-flare state, the rapid changes in the magnetic field associated with the flare occurrence, and the physical mechanisms behind these phenomena. Our picture of flare-productive ARs is summarized as follows: subject to the turbulent convection, the rising magnetic flux in the interior deforms into a complex structure and gains high non-potentiality; as the flux appears on the surface, an AR with large free magnetic energy and helicity is built, which is represented by -sunspots, sheared polarity inversion lines, magnetic flux ropes, etc; the flare occurs when sufficient magnetic energy has accumulated, and the drastic coronal evolution affects magnetic fields even in the photosphere. We show that the improvement of observational instruments and modeling capabilities has significantly advanced our understanding in the last decades. Finally, we discuss the outstanding issues and future perspective and further broaden our scope to the possible applications of our knowledge to space-weather forecasting, extreme events in history, and corresponding stellar activities. Electronic supplementary material The online version of this article (10.1007/s41116-019-0019-7) contains supplementary material, which is available to authorized users.

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Section: Discussionmentioning

confidence: 99%

Section: Solar Flares and Cmesmentioning

confidence: 99%

Section: Connection With Stellar Flares and Cmesmentioning

confidence: 99%

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Flare-productive active regions

Toriumi

Wang

2019

Living Rev Sol Phys

235

151

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“…Three‐dimensional null points take on a different character according to the eigenvalues of a matrix constructed from the magnetic field in the neighborhood of the null (Parnell et al, ). In the solar magnetic environment, for instance, these eigenvalues would determine whether a separatrix forms a dome which isolates a volume of the magnetic field or the separatrix is oriented vertically such that it forms a boundary between regions of open flux (DeRosa & Barnes, ).…”

Section: Introductionmentioning

confidence: 99%

Magnetic Connectivity in the Corona as a Source of Structure in the Solar Wind

et al. 2019

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Five decades of satellite data confirm that the solar wind contains many boundaries separating flow with distinct magnetic and plasma properties. Some speculate the boundaries in the solar wind found at Earth originate at the solar surface and are carried along with the expanding solar wind as fossil structures to 1 AU. This begs the question, is it the physics and magnetic structure above the photosphere that creates well‐defined boundaries between different magnetic flux regions at 1 AU in the solar wind? Magnetic boundaries in the corona exist all the time as topological features of null points in the field. These topological magnetic boundaries seem to be likely locations for plasma boundaries. It can be expected that these boundaries are typical locations where field line‐integrated quantities, such as field‐aligned current, experience large and abrupt changes. We perform three‐dimensional resistive magnetohydrodynamic simulations of the solar corona driven by photospheric foot point motions. We find that large and abrupt changes occur for field line‐integrated quantities across a magnetic topological boundary and the cause for these changes is the discontinuous mapping for magnetic field lines and thus for Alfvén waves across these boundaries. It is also demonstrated via in situ properties that thin layers of field‐aligned and perpendicular currents are frequently located at or close to topological boundaries.

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“…Until now, the key nonpotential parameters of ARs governing the eruptive character of solar flares are still unknown based on statistical results. Moreover, the access to open flux (open to the interplanetary space) is also thought to influence whether an X-class flare is likely to be eruptive (DeRosa & Barnes 2018).…”

Section: Introductionmentioning

confidence: 99%

Magnetic Flux and Magnetic Non-potentiality of Active Regions in Eruptive and Confined Solar Flares

Li,

Chen,

Hou

et al. 2021

Preprint

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With the aim of understanding how the magnetic properties of active regions (ARs) control the eruptive character of solar flares, we analyze 719 flares of Geostationary Operational Environmental Satellite (GOES) class ≥C5.0 during 2010−2019. We carry out the first statistical study that investigates the flarecoronal mass ejections (CMEs) association rate as function of the flare intensity and the AR characteristics that produces the flare, in terms of its total unsigned magnetic flux (Φ AR ). Our results show that the slope of the flare-CME association rate with flare intensity reveals a steep monotonic decrease with Φ AR . This means that flares of the same GOES class but originating from an AR of larger Φ AR , are much more likely confined. Based on an AR flux as high as 1.0×10 24 Mx for solartype stars, we estimate that the CME association rate in X100-class "superflares" is no more than 50%. For a sample of 132 flares ≥M2.0 class, we measure three non-potential parameters including the length of steep gradient polarity inversion line (L SGP IL ), the total photospheric free magnetic energy (E f ree ) and the area with large shear angle (A Ψ ). We find that confined flares tend to have larger values of L SGP IL , E f ree and A Ψ compared to eruptive flares. Each non-potential parameter shows a moderate positive correlation with Φ AR . Our results imply that Φ AR is a decisive quantity describing the eruptive character of a flare, as it provides a global parameter relating to the strength of the background field confinement.

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Does Nearby Open Flux Affect the Eruptivity of Solar Active Regions?

Cited by 16 publications

References 59 publications

Flare-productive active regions

Flare-productive active regions

Magnetic Connectivity in the Corona as a Source of Structure in the Solar Wind

Magnetic Flux and Magnetic Non-potentiality of Active Regions in Eruptive and Confined Solar Flares

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