Chromospheric Mass Motions and Intrinsic Sunspot Rotations for Noaa Active Regions 10484, 10486, and 10488 Using Isoon Data

Hardersen, P. S.; Balasubramaniam, Krishnan; Shkolyar, Svetlana

doi:10.1088/0004-637x/773/1/60

Cited by 4 publications

(4 citation statements)

References 45 publications

(80 reference statements)

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“…First of all, we must find the rotation center of the right leg of the filament. Second, once the center is determined, the 304 Å images are uncurled to a polar coordinate rθ frame from the initial Cartesian x -y frame (Brown et al 2003;Hardersen et al 2013). The circles around the axis of the filament leg are uncurled counterclockwise, starting from a northward pointing chord (the black line from the center to the north), as illustrated in Figure 1.…”

Section: Methodsmentioning

confidence: 99%

Kink Instability Evidenced by Analyzing the Leg Rotation of a Filament

Yan

Xue

Liu

et al. 2014

ApJ

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Kink instability is a possible mechanism for solar filament eruption. However, the twist of a solar filament is very difficult to directly measure from observation. In this paper, we carried out the measurement of the twist of a solar filament by analyzing its leg rotation. An inverse S-shaped filament in active region NOAA 11485 was observed by the Atmospheric Imaging Assembly (AIA) of Solar Dynamics Observatory (SDO) on 2012 May 22. During its eruption, the leg of the filament exhibited a significant rotation motion. The 304Å images were used to uncurl along the circles, whose centers are the axis of the filament's leg. The result shows that the leg of the filament rotated up to about 510 degrees (about 2.83π) around the axis of the filament within twenty-three minutes. The maximal rotation speed reached 100 degrees per minute (about 379.9 km/s at radius 18 ′′ ), which is the fastest rotation speed that has been reported. We also calculated the decay index along the polarity inversion line in this active region and found that the decline of the overlying field with height is not so fast enough to trigger the torus instability. According to the condition of kink instability, it is indicating that the kink instability is the trigger mechanism for the solar filament eruption.

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Section: Methodsmentioning

confidence: 99%

Kink Instability Evidenced by Analyzing the Leg Rotation of a Filament

Yan

Xue

Liu

et al. 2014

ApJ

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“…They are usually detected by visual inspections and, since this may cause a bias in the analysis of vortexes, efforts in developing automated detection methods have been recently performed (Kato and Wedemeyer, 2017;Rempel et al, 2017;Giagkiozis et al, 2018). In this work, we intend to contribute to the development of automated methods of vortex detection by using a well-known method of detection and classification of critical points (Helman and Hesselink, 1989) to identify converging vortexes by associating them with a specific kind of critical point.…”

Section: Critical Point Detection and Classificationmentioning

confidence: 99%

“…A critical point is characterized by a flow velocity given by v(x, y) = (0, 0) ij . Then, in a linear vector field approximation, to find the coordinates of the critical point, we have to solve a matrix equation like we can classify the critical point according to Helman and Hesselink (1989), as presented in Table 1. We find the eigenvalues by first reducing the Jacobian matrix to the upper Hessenberg form using the ELMHES function in IDL and then returning the eigenvalues by applying the HQR function.…”

Section: Critical Point Detection and Classificationmentioning

confidence: 99%

Converging photospheric vortex flows close to the polarity inversion line of a fully emerged active region

Santos

Wrasse

2019

Ann. Geophys.

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Abstract. We report on the occurrence of vortexes in flow fields obtained from the evolution of the line-of-sight component of the photospheric magnetic field in a region around the polarity inversion line (PIL) of a fully emerged active region. Based on a local linear approximation for the flow field, we identify the presence of critical points and classify them according to the eigenvalues of the Jacobian matrix of the linear transformation. Converging vortexes are associated with the presence of a particular kind of critical point, known as the attracting focus. We identified 12 converging vortexes in the analyzed period and detected the occurrence of other types of critical points, which indicate the complexity of the flow field around the PIL. The detected vortexes show a clockwise preferred sense of rotation with approximately 67 % of the cases. A geometrical analysis of the velocity structures produced an average value of D‾=1.63±0.05 for the fractal dimension, which is very close to the one obtained for isotropic homogeneous turbulence (D=5/3). This suggests that the flow around the PIL is turbulent in nature.

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“…On larger scales, rotational motions were observed in sunspots and they are usually associated with energy and helicity buildup and later release by flare and/or coronal mass ejection (Brown et al, 2003;Hiremath and Suryanarayana, 2003;Hiremath et al, 2005;Yan and Qu, 2007;Yan et al, 2008;Min and Chae, 2009;Yan et al, 2009;Kazachenko et al, 2010;Zhu et al, 2012;Yan et al, 2012;Jiang et al, 2012;Vemareddy et al, 2012;Hardersen et al, 2013;Wang et al, 2014;Ruan et al, 2014;Gopasyuk, 2015;Li and Liu, 2015;Suryanarayana et al, 2015;Wang et al, 2016;Vemareddy et al, 2016). The rotation of sunspots is usually very slow, this means that the evolution of the magnetic field in the corona associated to it would be slow as well.…”

Section: Introductionmentioning

confidence: 99%

Photospheric vortex flows close to the polarity inversion line of a fully emerged active region

Santos

Wrasse

2019

Preprint

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Abstract. We report on the occurrence of vortexes in flow fields obtained from the evolution of the line-of-sight component of the photospheric magnetic field in a region around the polarity inversion line of a fully emerged active region. Based on a local linear approximation for the flow field, we identify the presence of critical points and classify them according to the eigenvalues of the Jacobian matrix of the linear transformation. Vortexes are associated to the presence of a particular kind of critical point, known as Attracting Focus. Using this method we identified twelve vortexes in the analyzed period and detected the occurrence of other types of critical points, which indicate the complexity of the flow field around the PIL. The detected vortexes show a clockwise preferred sense of rotation with approximately 67 % of the cases. A geometrical analysis of the velocity structures produced an average value of D = 1.63 ± 0.05 for the fractal dimension, which is very close to the one obtained for isotropic homogeneous turbulence (D = 5/3). This suggests that the flow around the polarity inversion line is turbulent in nature.

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Chromospheric Mass Motions and Intrinsic Sunspot Rotations for Noaa Active Regions 10484, 10486, and 10488 Using Isoon Data

Cited by 4 publications

References 45 publications

Kink Instability Evidenced by Analyzing the Leg Rotation of a Filament

Kink Instability Evidenced by Analyzing the Leg Rotation of a Filament

Converging photospheric vortex flows close to the polarity inversion line of a fully emerged active region

Photospheric vortex flows close to the polarity inversion line of a fully emerged active region

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