The variation of filament direction in a flaring region

Rausaria, R. R.; Raman, Kumar; Aleem, P. S. M.; Singh, Jagdev

doi:10.1007/bf00662175

Cited by 12 publications

(4 citation statements)

References 6 publications

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“…Tlatov et al (2016a,b) using synoptic charts from Meudon observatory and Kislovodsk Mountain Astronomical station studied variation of filament tilt angle and classified filaments with different tilt angle viz., active region filaments, quiescent filaments and polar filaments. There have been some works from Kodaikanal historical data on prominences (Ananthakrishnan 1952;Evershed 1907Evershed , 1908Rausaria et al 1993a), flares (Rausaria et al 1993b;Sundara Raman et al 1994, 2001. Most of these earlier studies were for shorter period of time.…”

Section: Introductionmentioning

confidence: 99%

Long-term Study of the Solar Filaments from the Synoptic Maps as Derived from Spectroheliograms of the Kodaikanal Observatory

Chatterjee

Hegde

Banerjee

et al. 2017

ApJ

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The century long H α (656.28 nm) spectroheliograms from Kodaikanal Solar Observatory (KSO) have been recently digitised. Using these newly calibrated, processed images we study the evolution of dark elongated on disk structures called filaments, potential representatives of magnetic activities on the Sun. To our knowledge this is the oldest uniform digitised dataset with daily images available today in H α . We generate Carrington maps for entire time duration and try to find the correspondences with maps of same rotation from Ca II K KSO data. Filaments are segmented from Carrington maps using a semi-automated technique and are studied individually to extract their centroids and tilts. We plot the time-latitude distribution of filament centroids producing Butterfly diagram, which clearly shows presence of poleward migration. We separate polar filaments for each cycle and try to estimate the delay between the polar filament number cycle and sunspot number cycle peaks. We correlate this delay with the same between polar reversal and sunspot number maxima.This provides new insight on the role of polar filaments on polar reversal.

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Section: Introductionmentioning

confidence: 99%

Long-term Study of the Solar Filaments from the Synoptic Maps as Derived from Spectroheliograms of the Kodaikanal Observatory

Chatterjee

Hegde

Banerjee

et al. 2017

ApJ

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“…There are several characteristics of active regions which favor causing flares. If active regions have strong magnetic gradients (Wang et al 1994(Wang et al , 2006, highly sheared transverse magnetic fields (Rausaria et al 1993;Chen et al 1994;Wang et al 1996), emerging fluxes (Schmieder et al 1997;Chen & Shibata 2000;Liu & Zhang 2001;Zhang 2006), and flux cancellation (Wang & Shi 1993;, flares are triggered more often. Besides the observations mentioned above, sunspot rotation (Evershed 1910;Nightingale et al 2001Nightingale et al , 2002Brown et al 2003;) may be involved with energy buildup and the energy is released later via flares (Stenflo 1969;Régnier et al 2006;Yan et al 2007.…”

Section: Introductionmentioning

confidence: 99%

The causality between the rapid rotation of a sunspot and an X3.4 flare

Yan¹,

Qu²,

Xu³

et al. 2009

Res. Astron. Astrophys.

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Using multi-wavelength data of Hinode, a rapid rotation of a sunspot in active region NOAA 10930 is studied in detail. We found the extra-ordinary counterclockwise rotation of the sunspot with positive polarity before an X3.4 flare. From a series of vector magnetograms, it is found that the magnetic force lines highly sheared along the neutral line accompanying the sunspot rotation. Furthermore, it is also found that the sheared loops and an inverse S-shaped magnetic loop in the corona formed gradually after the sunspot rotation.The X3.4 flare can be reasonably regarded as a result of this movement. The detailed analysis provides an evidence that sunspot rotation leads to magnetic field lines twisting in the photosphere, the twist is then transported into the corona, and finally flares are triggered.Abstract Using multi-wavelength data of Hinode, a rapid rotation of a sunspot in active region NOAA 10930 is studied in detail. We found the extra-ordinary counterclockwise rotation of the sunspot with positive polarity before an X3.4 flare. From a series of vector magnetograms, it is found that the magnetic force lines highly sheared along the neutral line accompanying the sunspot rotation. Furthermore, it is also found that the sheared loops and an inverse S-shaped magnetic loop in the corona formed gradually after the sunspot rotation.The X3.4 flare can be reasonably regarded as a result of this movement. The detailed analysis provides an evidence that sunspot rotation leads to magnetic field lines twisting in the photosphere, the twist is then transported into the corona, and finally flares are triggered.

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“…For instance, after the appearance of a flare, the shear angle may decrease (Rausaria et al 1993), stay unchanged (Chen et al 1994), or even increase (Wang et al 1993. On the other hand, other authors have studied the correlation between the variations of the photospheric magnetic field and flares.…”

Section: Introductionmentioning

confidence: 99%

Rapid rotation of a sunspot associated with flares

Yan

2007

A&A

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Context. Active region NOAA 10424 observed on August 5, 2003 is studied in detail by using TRACE, SOHO/MDI, BBSO Hα monograph, and GOES data. This investigation focuses on the sunspot rotation and its relation with the eruptive phenomena by analyzing the magnetic configuration that the rotation results in. Aims. It is shown that there is a close relationship between the sunspot rotation and the emerging kinked magnetic Ω-loops, where the flares occur. Methods. Through tracing the traceable features motion by using the TRACE white-light images, one can get the rotation velocities of the umbra, the penumbra, the area near the penumbra, and the area far from the penumbra. Furthermore, the evolution of the emerging kinked magnetic Ω-loops and magnetic fields were studied. Results. For the sunspot with positive polarity, the umbra, the penumbra, and the area near the penumbra exhibit a conspicuous counterclockwise rotation. Moreover, the velocities decrease from the umbra through the penumbra to the area near the penumbra. It is interesting that the rotation of the umbra, the penumbra, and the area near the penumbra are opposite to that of the area far from penumbra. The rotation velocities of the umbra, the penumbra, polarity separation, and total magnetic flux increase with time. During the largest event (M1.7/Sn flare), emerging kinked magnetic Ω-loops are observed from TRACE 171 Å images. Conclusions. The different rotation speeds of the different parts of the sunspot cause twist, and then the twist is injected through the chromosphere into the corona to trigger the flares.

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The variation of filament direction in a flaring region

Cited by 12 publications

References 6 publications

Long-term Study of the Solar Filaments from the Synoptic Maps as Derived from Spectroheliograms of the Kodaikanal Observatory

Long-term Study of the Solar Filaments from the Synoptic Maps as Derived from Spectroheliograms of the Kodaikanal Observatory

The causality between the rapid rotation of a sunspot and an X3.4 flare

Rapid rotation of a sunspot associated with flares

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