The Proper Motion of Individual Sunspots

Herdiwijaya, Dhani; Makita, M.; Anwar, Bachtiar

doi:10.1093/pasj/49.2.235

Cited by 16 publications

(8 citation statements)

References 1 publication

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“…The splitting of the leading sunspot in this investigation is initiated by a stretching instead of light bridge formation, and proceeds within about a day, so much faster than usual. While the front half separates from the active region at a considerable speed of 210 m s −1 (consistent with the values reported in Herdiwijaya et al 1997) and shows strong rotation, as well as considerable shear flows, the rear half stays essentially stationary within the active region without any signs of rotation or shear flows. The rotation rate of the runaway sunspot equals the highest rotation rate of a single sunspot found previously (compare, e.g., with Brown et al 2003;Zhang et al 2008a;Yan et al 2012); thus, it is a further unusual property of the splitting process in the considered event.…”

Section: Splitting Of the Sunspotsupporting

confidence: 87%

Sunspot splitting triggering an eruptive flare

Louis

Puschmann

Kliem

et al. 2014

A&A

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Aims. We investigate how the splitting of the leading sunspot and associated flux emergence and cancellation in active region NOAA 11515 caused an eruptive M5.6 flare on 2012 July 2. Methods. Continuum intensity, line-of-sight magnetogram, and dopplergram data of the Helioseismic and Magnetic Imager were employed to analyse the photospheric evolution. Filtergrams in Hα and He i 10830 Å of the Chromospheric Telescope at the Observatorio del Teide, Tenerife, track the evolution of the flare. The corresponding coronal conditions were derived from 171 Å and 304 Å images of the Atmospheric Imaging Assembly. Local correlation tracking was utilized to determine shear flows. Results. Emerging flux formed a neutral line ahead of the leading sunspot and new satellite spots. The sunspot splitting caused a longlasting flow towards this neutral line, where a filament formed. Further flux emergence, partly of mixed polarity, as well as episodes of flux cancellation occurred repeatedly at the neutral line. Following a nearby C-class precursor flare with signs of interaction with the filament, the filament erupted nearly simultaneously with the onset of the M5.6 flare and evolved into a coronal mass ejection. The sunspot stretched without forming a light bridge, splitting unusually fast (within about a day, complete ≈6 h after the eruption) in two nearly equal parts. The front part separated strongly from the active region to approach the neighbouring active region where all its coronal magnetic connections were rooted. It also rotated rapidly (by 4.9• h −1 ) and caused significant shear flows at its edge. Conclusions. The eruption resulted from a complex sequence of processes in the (sub-)photosphere and corona. The persistent flows towards the neutral line likely caused the formation of a flux rope that held the filament. These flows, their associated flux cancellation, the emerging flux, and the precursor flare all contributed to the destabilization of the flux rope. We interpret the sunspot splitting as the separation of two flux bundles differently rooted in the convection zone and only temporarily joined in the spot. This explains the rotation as the continued rise of the separating flux, and it implies that at least this part of the sunspot was still connected to its roots deep in the convection zone.

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Section: Splitting Of the Sunspotsupporting

confidence: 87%

Sunspot splitting triggering an eruptive flare

Louis

Puschmann

Kliem

et al. 2014

A&A

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“…The proper motion of magnetic features such as these has been observed on the solar surface, for example, sunspots have been seen to drift at speeds of 0.14 km s -1 Herdiwijaya et al (1997) and moving magnetic features within sunspots move at ∼ 0.5 km s -1 Zhang et al (2007). Rotational motion of magnetic features has also been observed, the rotational velocity of sunspots has been measured at values of up to ∼ 3.8 • hr -1 during their emergence from the photosphere Zhu et al (2012).…”

Section: Discussionmentioning

confidence: 95%

The Effects of Oscillations & Collisions of Emerging Bipolar Regions on the Triggering of Solar Flares

Boocock,

Kusano,

Tsiklauri

2020

Preprint

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The ability to predict the occurrence of solar flares in advance is important to humankind due to the potential damage they can cause to Earth's environment and infrastructure. It has been shown in Kusano et al. (2012) that a small-scale bipolar region (BR), with its flux reversed relative to the potential component of the overlying field, appearing near the polarity inversion line (PIL) is sufficient to effectively trigger a solar flare. In this study we perform further 3D magnetohydrodynamic simulations to study the effect that the motion of these small-scale BRs has on the effectiveness of flare triggering. The effect of two small-scale BRs colliding is also simulated. The results indicate that the strength of the triggered flare is dependent on how much of the overlying field is disrupted by the BR. Simulations of linear oscillations of the BR showed that oscillations along the PIL increase the flare strength whilst oscillations across the PIL detract from the flare strength. The flare strength is affected more by larger amplitude oscillations but is relatively insensitive to the frequency of oscillations. In the most extreme case the peak kinetic energy of the flare increased more than threefold compared to a non-oscillating BR. Simulations of torsional oscillations of the BR showed a very small effect on the flare strength. Finally, simulations of colliding BRs showed the generation of much stronger flares as the flares triggered by each individual BR coalesce. These results show that significantly stronger flares can result from motion of the BR along the PIL of a sheared field or from the presence of multiple BRs in the same region.

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“…It should be noted that a CME is not simply the explosive result of a flare, but has its own magnetic driver. Strong shock waves are expected to develop from fast CMEs [11].…”

Section: Theory Of Coronal Mass Ejections (Cmes)mentioning

confidence: 99%

The Propagation of an Impulsive Coronal Mass Ejections (CMEs) due to the High Solar Flares and Moreton Waves

Hamidi

Shariff

2014

ILCPA

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This paper provides a short review of some of the basic concepts related to the origin of Coronal Mass Ejections (CMEs). The numerous ideas which have been put forward to elucidate the initiation of CMEs are categorized in terms of whether this event is a gradual CME or impulsive CME. In this case, an earth-directed Coronal Mass Ejection (CME) was observed on April 2, 2014 by the Large Angle Spectrometric Coronagraph (LASCO) C2. This recent observations obtained a large impulsive CMEs. The CME, originating from the active region AR2027. The speed of CMEs is 1600 kms -1 . A halo CME, a bright expanding ring at the North-West region is exploded beginning at about 14:36 UT, and the process of departing, expansion and propagation are highlighted. We discuss the correspondence of this event with the structure of the CME in the LASCO data. It is believed that the high solar flare and a Moreton waves initiate this kind of CMEs.

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The Proper Motion of Individual Sunspots

Cited by 16 publications

References 1 publication

Sunspot splitting triggering an eruptive flare

Sunspot splitting triggering an eruptive flare

The Effects of Oscillations & Collisions of Emerging Bipolar Regions on the Triggering of Solar Flares

The Propagation of an Impulsive Coronal Mass Ejections (CMEs) due to the High Solar Flares and Moreton Waves

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