Velocity and Magnetic Transients Driven by the X2.2 White-Light Flare of 2011 February 15 in Noaa 11158

Maurya, Ram Ajor; Vemareddy, P.; Ambastha, Ashok

doi:10.1088/0004-637x/747/2/134

Cited by 51 publications

(46 citation statements)

References 34 publications

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“…This is three times larger than the derived energy from coronal magnetic field extrapolations by Sun et al (2012) over the entire AR. Spectral line-profile reversals occurred during the impulsive phase of this flare, affecting the magnetic and velocity field measurements, as reported recently by Maurya et al (2012). As a result, the injected helicity rate shows an impulsive negative peak because of the sudden appearance of negative helicity density, which indicates flare-related transient effect (cf.…”

Section: Discussionsupporting

confidence: 71%

On the Role of Rotating Sunspots in the Activity of Solar Active Region Noaa 11158

Vemareddy

Ambastha

Maurya

2012

ApJ

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We study the role of rotating sunspots in relation to the evolution of various physical parameters characterizing the non-potentiality of the active region (AR) NOAA 11158 and its eruptive events using the magnetic field data from the Helioseismic and Magnetic Imager (HMI) and multi-wavelength observations from the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory. From the evolutionary study of HMI intensity and AIA channels, it is observed that the AR consists of two major rotating sunspots, one connected to a flare-prone region and another with coronal mass ejection (CME). The constructed space-time intensity maps reveal that the sunspots exhibited peak rotation rates coinciding with the occurrence of major eruptive events. Further, temporal profiles of twist parameters, namely, average shear angle, α av , α best , derived from HMI vector magnetograms, and the rate of helicity injection, obtained from the horizontal flux motions of HMI line-of-sight magnetograms, correspond well with the rotational profile of the sunspot in the CME-prone region, giving predominant evidence of rotational motion causing magnetic non-potentiality. Moreover, the mean value of free energy from the virial theorem calculated at the photospheric level shows a clear step-down decrease at the onset time of the flares revealing unambiguous evidence of energy release intermittently that is stored by flux emergence and/or motions in pre-flare phases. Additionally, distribution of helicity injection is homogeneous in the CME-prone region while in the flare-prone region it is not and often changes sign. This study provides a clear picture that both proper and rotational motions of the observed fluxes played significant roles in enhancing the magnetic non-potentiality of the AR by injecting helicity, twisting the magnetic fields and thereby increasing the free energy, leading to favorable conditions for the observed transient activity.

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Section: Discussionsupporting

confidence: 71%

On the Role of Rotating Sunspots in the Activity of Solar Active Region Noaa 11158

Vemareddy

Ambastha

Maurya

2012

ApJ

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“…The magnetic transients occurred during the X5.4 and X1.3 flares were co-spatial with flare ribbons. This is consistent with Maurya et al (2012), who found that magnetic transients in AR 11158 during a X2.2 flare persisted for a few minutes and showed co-spatial with flare ribbons, which were separating out with a mean velocity of 8 km s −1 . During the evolution of sunspots (N1, N2 and N3), changes in the trend of magnetic field evolution were presented, and are associated with the two X-class flares.…”

Section: Summary and Discussionsupporting

confidence: 92%

Sunspot rotation and magnetic transients associated with flares in NOAA AR 11429

Zheng

Yang

Guo

et al. 2017

Res. Astron. Astrophys.

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We analyze sunspots rotation and magnetic transients in NOAA AR 11429 during two X-class (X5.4 and X1.3) flares using the data from the Helioseismic and Magnetic Imager on board the Solar Dynamics Observatory. A large leading sunspot with positive magnetic polarity rotated counterclockwise. As expected, the rotation was significantly affected by the two flares. The magnetic transients induced by the flares were clearly evident in the sunspots with negative polarity. They were moving across the sunspots with speed of order 3 − 7 km s −1 . Furthermore, the trend of magnetic flux evolution of these sunspots exhibited changes associated with the flares. These results may shed light on the understanding of the evolution of sunspots.

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“…Next, we consider AR 11158 ( Figure 5), which was a rapidly growing AR that produced the first X-class flare of solar cycle 24 on 2011 February 15 (Maurya et al 2012) with an Earth-directed halo coronal mass ejection (Schrijver et al 2011). It also produced several Mclass flares during February 13-16 (Inoue et al 2013), after being assigned its number on February 13.…”

Section: Isolated Arsmentioning

confidence: 99%

HIGH-WAVENUMBER SOLAR f-MODE STRENGTHENING PRIOR TO ACTIVE REGION FORMATION

Singh

Raichur

Brandenburg

2016

ApJ

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We report a systematic strengthening of the local solar surface or fundamental f -mode 1-2 days prior to the emergence of an active region (AR) in the same (corotating) location. Except for a possibly related increase in the kurtosis of the magnetic field, no indication can be seen in the magnetograms at that time. Our study is motivated by earlier numerical findings of Singh et al. (2014) which showed that, in the presence of a nonuniform magnetic field that is concentrated a few scale heights below the surface, the f -mode fans out in the diagnostic kω diagram at high wavenumbers. Here we explore this possibility using data from the Helioseismic and Magnetic Imager on board the Solar Dynamics Observatory and show for six isolated ARs, 11130, 11158, 11242, 11105, 11072, and 11768, that at large latitudinal wavenumbers (corresponding to horizontal scales of around 3000 km), the f -mode displays strengthening about two days prior to AR formation and thus provides a new precursor for AR formation. Furthermore, we study two ARs, 12051 and 11678, apart from a magnetically quiet patch lying next to AR 12529, to demonstrate the challenges in extracting such a precursor signal when a newly forming AR emerges in a patch that lies in close proximity of one or several already existing ARs which are expected to pollute neighboring patches. We then discuss plausible procedures for extracting precursor signals from regions with crowded environments. The idea that the f -mode is perturbed days before any visible magnetic activity occurs at the surface can be important in constraining dynamo models aimed at understanding the global magnetic activity of the Sun.

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Velocity and Magnetic Transients Driven by the X2.2 White-Light Flare of 2011 February 15 in Noaa 11158

Cited by 51 publications

References 34 publications

On the Role of Rotating Sunspots in the Activity of Solar Active Region Noaa 11158

On the Role of Rotating Sunspots in the Activity of Solar Active Region Noaa 11158

Sunspot rotation and magnetic transients associated with flares in NOAA AR 11429

HIGH-WAVENUMBER SOLAR f-MODE STRENGTHENING PRIOR TO ACTIVE REGION FORMATION

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