Record-breaking Coronal Magnetic Field in Solar Active Region 12673

Anfinogentov, Sergey; Stupishin, A. G.; Myshyakov, I. I.; Fleishman, G. D.

doi:10.3847/2041-8213/ab3042

Cited by 56 publications

(43 citation statements)

References 24 publications

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“…Several significant coronal mass ejections (CMEs) were launched during its disk passage (Redmon et al 2018). Furthermore, this "monster" active region exhibited highly unusual characteristics and extreme behavior including the fastest flux emergence ever recorded (Sun & Norton 2017), the strongest transverse, (Wang et al 2018) and coronal magnetic fields (Anfinogentov et al 2019). Figure 1 includes an animation of these data for 2017 September 1-7.…”

Section: Magnetic Field Evolution Of Ar 12673mentioning

confidence: 99%

Can Subphotospheric Magnetic Reconnection Change the Elemental Composition in the Solar Corona?

Baker

Driel-Gesztelyi

Brooks

et al. 2020

ApJ

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Within the coronae of stars, abundances of those elements with low first ionization potential (FIP) often differ from their photospheric values. The coronae of the Sun and solar-type stars mostly show enhancements of low-FIP elements (the FIP effect) while more active stars such as M dwarfs have coronae generally characterized by the inverse-FIP effect (I-FIP). Here we observe patches of I-FIP effect solar plasma in AR 12673, a highly complex βγδ active region. We argue that the umbrae of coalescing sunspots, and more specifically strong light bridges within the umbrae, are preferential locations for observing I-FIP effect plasma. Furthermore, the magnetic complexity of the active region and major episodes of fast flux emergence also lead to repetitive and intense flares. The induced evaporation of the chromospheric plasma in flare ribbons crossing umbrae enables the observation of four localized patches of I-FIP effect plasma in the corona of AR 12673. These observations can be interpreted in the context of the ponderomotive force fractionation model which predicts that plasma with I-FIP effect composition is created by the refraction of waves coming from below the chromosphere. We propose that the waves generating the I-FIP effect plasma in solar active regions are generated by subphotospheric reconnection of coalescing flux systems. Although we only glimpse signatures of I-FIP effect fractionation produced by this interaction in patches on the Sun, on highly active M stars it may be the dominant process.

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Section: Magnetic Field Evolution Of Ar 12673mentioning

confidence: 99%

Can Subphotospheric Magnetic Reconnection Change the Elemental Composition in the Solar Corona?

Baker

Driel-Gesztelyi

Brooks

et al. 2020

ApJ

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“…Radio spectral observations of type III bursts, spike structures associated with type IV bursts and zebra patterns could also provide estimates of the magnetic field in the coronal source regions of the radio emission [21][22][23]. In addition, when the emission mechanisms are known, microwave imaging at one or more frequencies could be used to produce maps of the coronal magnetic field strength in limited regions [24][25][26][27][28][29]. More recently, the phenomenon of magnetic-fieldinduced transition (MIT) [30] has caught the attention of the solar physics community, and theoretical and laboratory investigations have demonstrated the potential of MIT lines in measurements of the coronal magnetic field [31][32][33].…”

Section: Introductionmentioning

confidence: 99%

Mapping the magnetic field in the solar corona through magnetoseismology

Yang

Tomczyk

Morton

et al. 2020

Sci. China Technol. Sci.

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of magnetic field diagnostics based on observations of magnetohydrodynamic (MHD) waves, has been widely used to estimate the field strengths of oscillating structures in the solar corona. However, previously magnetoseismology was mostly applied to occasionally occurring oscillation events, providing an estimate of only the average field strength or one-dimensional distribution of field strength along an oscillating structure. This restriction could be eliminated if we apply magnetoseismology to the pervasive propagating transverse MHD waves discovered with the Coronal Multi-channel Polarimeter (CoMP). Using several CoMP observations of the Fe xiii 1074.7 nm and 1079.8 nm spectral lines, we obtained maps of the plasma density and wave phase speed in the corona, which allow us to map both the strength and direction of the coronal magnetic field in the plane of sky. We also examined distributions of the electron density and magnetic field strength, and compared their variations with height in the quiet Sun and active regions. Such measurements could provide critical information to advance our understanding of the Sun's magnetism and the magnetic coupling of the whole solar atmosphere.

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“…As we know, this has not been observed before. Numerical simulation of the magnetic structure and gyroresonance emission of NOAA 12673 in [Anfinogentov et al, 2019] has shown that the NLS observed at 17 and 34 GHz corresponded to the unusually high magnetic field strength detected at the photospheric level.…”

Section: Active Region Noaa 12673mentioning

confidence: 96%

Microwave indicator of potential geoeffectiveness and magnetic flux-rope structure of a solar active region

Kudriavtseva

Myshyakov

Uralov

et al. 2021

Solar-Terrestrial Physics

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We analyze the presence of a microwave neutral-line-associated source (NLS) in a super-active region NOAA 12673, which produced a number of geo-effective events in September 2017. To estimate the NLS position, we use data from the Siberian Radioheliograph in a range 4–8 GHz and from the Nobeyama Radioheliograph at 17 GHz. Calculation of the coronal magnetic field in a non-linear force-free approximation has revealed an extended structure consisting of interconnected magnetic flux ropes, located practically along the entire length of the main polarity separation line of the photospheric magnetic field. NLS is projected into the region of the strongest horizontal magnetic field, where the main energy of this structure is concentrated. During each X-class flare, the active region lost magnetic helicity and became a CME source.

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Record-breaking Coronal Magnetic Field in Solar Active Region 12673

Cited by 56 publications

References 24 publications

Can Subphotospheric Magnetic Reconnection Change the Elemental Composition in the Solar Corona?

Can Subphotospheric Magnetic Reconnection Change the Elemental Composition in the Solar Corona?

Mapping the magnetic field in the solar corona through magnetoseismology

Microwave indicator of potential geoeffectiveness and magnetic flux-rope structure of a solar active region

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