STUDY ON THE TRIGGERING PROCESS OF SOLAR FLARES BASED ON<i>HINODE</i>/SOT OBSERVATIONS

Bamba, Yumi; Kusano, K.; Yamamoto, T.; Okamoto, Takenori J.

doi:10.1088/0004-637x/778/1/48

Cited by 62 publications

(89 citation statements)

References 22 publications

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“…With this shear and according to these simulations, the injected kinetic energy might be large enough to provoke an eruption. Bamba et al (2013) states that OP-type may influence the destabilization of a flux rope via reconnection.…”

Section: Discussionmentioning

confidence: 99%

Supergranular-scale magnetic flux emergence beneath an unstable filament

Palacios

Cid

Guerrero

et al. 2015

A&A

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Aims. Here we report evidence of a large solar filament eruption on 2013, September 29. This smooth eruption, which passed without any previous flare, formed after a two-ribbon flare and a coronal mass ejection towards Earth. The coronal mass ejection generated a moderate geomagnetic storm on 2013, October 2 with very serious localized effects. The whole event passed unnoticed to flarewarning systems. Methods. We have conducted multi-wavelength analyses of the Solar Dynamics Observatory through Atmospheric Imaging Assembly (AIA) and Helioseismic and Magnetic Imager (HMI) data. The AIA data on 304, 193, 211, and 94 Å sample the transition region and the corona, respectively, while HMI provides photospheric magnetograms, continuum, and linear polarization data, in addition to the fully inverted data provided by HMI.Results. This flux emergence happened very close to a filament barb that was very active in mass motion, as seen in 304 Å images. The observed flux emergence exhibited hectogauss values. The flux emergence extent appeared just beneath the filament, and the filament rose during the following hours. The emergence acquired a size of 33 in ∼12 h, about ∼0.16 km s −1 . The rate of signed magnetic flux is around 2 × 10 17 Mx min −1 for each polarity. We have also studied the eruption speed, size, and dynamics. The mean velocity of the rising filament during the ∼40 min previous to the flare is 115 ± 5 km s −1 , and the subsequent acceleration in this period is 0.049 ± 0.001 km s −2 . Conclusions. We have observed a supergranular-sized emergence close to a large filament in the boundary of the active region NOAA11850. Filament dynamics and magnetogram results suggest that the magnetic flux emergence takes place in the photospheric level below the filament. Reconnection occurs underneath the filament between the dipped lines that support the filament and the supergranular emergence. The very smooth ascent is probably caused by this emergence and torus instability may play a fundamental role, which is helped by the emergence.

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Section: Discussionmentioning

confidence: 99%

Supergranular-scale magnetic flux emergence beneath an unstable filament

Palacios

Cid

Guerrero

et al. 2015

A&A

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“…Reversed shear polarity refers to the small bipole structure which is directed nearly opposite to the shear component of the field. In order to examine the model of the solar flare trigger mechanism proposed by Kusano et al (2012), several observational analyses of flare events have been conducted by using Hinode (Kusano et al 2012;Bamba et al 2013;Toriumi et al 2013), SDO (Bamba et al 2014), SOHO/MDI (Park et al 2013), and New Solar Telescope (NST) data (Wang et al 2017). From their results, several flare events can be explained to occur as a result of the flare trigger mechanism proposed in Kusano et al (2012).…”

Section: Introductionmentioning

confidence: 99%

Magnetohydrodynamic Simulations for Studying Solar Flare Trigger Mechanism

Muhamad¹,

Kusano²,

Inoue³

et al. 2017

ApJ

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In order to understand the flare trigger mechanism, we conducted threedimensional magnetohydrodynamic simulations using a coronal magnetic field model derived from data observed by the Hinode satellite. Several types of magnetic bipoles were imposed into the photospheric boundary of the Non-linear Force-Free Field (NLFFF) model of Active Region NOAA 10930 on 2006 December 13 to investigate what kind of magnetic disturbance may trigger the flare. As a result, we confirm that certain small bipole fields, which emerge into the highly sheared global magnetic field of an active region, can effectively trigger a flare. These bipole fields can be classified into two groups based on their orientation relative to the polarity inversion line: the so called opposite polarity (OP) and reversed shear (RS) structures as it was suggested by Kusano et al. (2012). We also investigated the structure of the footpoints of reconnected field lines. By comparing the distribution of reconstructed field lines and the observed flare ribbons, the trigger structure of the flare can be inferred. Our simulation suggests that the data-constrained simulation taking into account both the large-scale magnetic structure and the small-scale magnetic disturbance such as emerging fluxes is a good way to find out a flare productive active region for space weather prediction.

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“…A series of powerful flares erupted in this super active region in Solar Cycle 22 (cf. Sakurai et al, 1992;Bumba et al, 1993;Liu et al, 1996;Ji et al, 1998Ji et al, , 2003Schmieder et al, 1994;Zhang and Wang, 1994;Yan and Wang, 1995;Yan et al, 1995;Zhang, 1995Zhang, , 1996Zhang, , 2001Wang, 1997;Wang et al, 2006). Figure 2 also shows the relationship among the observed highly twisted vector magnetic fields, the calculated potential and non-potential magnetic fields, and the corresponding magnetic free energy densities in the super active region NOAA 6580-6619-6659 in 1991.…”

Section: Recurrent Active Region Noaa 6580-6619-6659mentioning

confidence: 99%

Photospheric Magnetic Free Energy Density of Solar Active Regions

Zhang¹

2016

Sol Phys

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We present the photospheric energy density of magnetic fields in two solar active regions (one of them recurrent) inferred from observational vector magnetograms, and compare it with other available differently defined energy parameters of magnetic fields in the photosphere. We analyze the magnetic fields in Active Regions NOAA 6580-6619-6659 and 11158. The quantity 1 4π B n · B p is an important energy parameter that reflects the contribution of magnetic shear to the difference between the potential (B p ) and the non-potential magnetic field (B n ), and also the contribution to the free magnetic energy near the magnetic neutral lines in the active regions. It is found that the photospheric mean magnetic energy density shows clear changes before the powerful solar flares in Active Region NOAA 11158, which is consistently with the change of magnetic fields in the flaring lower atmosphere.

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STUDY ON THE TRIGGERING PROCESS OF SOLAR FLARES BASED ONHINODE/SOT OBSERVATIONS

Cited by 62 publications

References 22 publications

Supergranular-scale magnetic flux emergence beneath an unstable filament

Supergranular-scale magnetic flux emergence beneath an unstable filament

Magnetohydrodynamic Simulations for Studying Solar Flare Trigger Mechanism

Photospheric Magnetic Free Energy Density of Solar Active Regions

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