Observational Evidence of Changing Photospheric Vector Magnetic Fields Associated With Solar Flares

Su, Jiangtao; Jing, Ju; Wang, H. M.; Mao, Xinjie; Wang, Xiaofeng; Zhang, H. Q.; Deng, Yuanyong; Guo, Jingjing; Wang, G. P.

doi:10.1088/0004-637x/733/2/94

Cited by 18 publications

(11 citation statements)

References 32 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Flare-associated changes in white-light continuum intensities have also been found in previous studies (Wang et al2004;Deng et al 2005;Liu et al 2005;Chen et al 2007;Li et al 2009;Su et al 2011). It is often found that regions in the outer penumbra of a δ-spot active region become brighter after the flare whereas regions in the inner penumbra that is near to the flaring PIL become darker after the flare (e.g.…”

Section: Introductionsupporting

confidence: 75%

On the Relationship Between Sunspot Structure and Magnetic Field Changes Associated With Solar Flares

Song

Zhang

2016

ApJ

View full text Add to dashboard Cite

Many previous studies have shown that magnetic fields as well as sunspot structures present rapid and irreversible changes associated with solar flares. In this paper we first use five X-class flares observed by SDO/HMI to show that not only the magnetic fields and sunspot structures do show rapid, irreversible changes but also these changes are closely related, both spatially and temporally.The magnitudes of the correlation coefficients between the temporal variations of horizontal magnetic field and sunspot intensity are all larger than 0.90, with a maximum value of 0.99 and an average value of 0.96. Then using four active regions in quiescent times, three observed and one simulated, we show that in sunspot penumbra regions there also exists a close correlation between sunspot intensity and horizontal magnetic field strength, in addition to the well-known one between sunspot intensity and normal magnetic field strength. Connecting these two observational phenomena, we show that the sunspot structure change and the magnetic field change are the two facets of the same phenomena of solar flares, one change might be induced by the change of the other due to a linear correlation between sunspot intensity and magnetic field strength out of a local force balance.

show abstract

Section: Introductionsupporting

confidence: 75%

On the Relationship Between Sunspot Structure and Magnetic Field Changes Associated With Solar Flares

Song

Zhang

2016

ApJ

View full text Add to dashboard Cite

show abstract

“…Namely, the transverse field near the magnetic polarity inversion line (PIL) at the core flaring region is enhanced rapidly and irreversibly, which is often accompanied by an increase of magnetic shear. Such a rapid change of vector PMFs closely associated with flares/CMEs has been consistently found later on using ground-based (Schmieder et al 1994;Wang et al 2002Wang et al , 2004bWang et al , 2005Wang et al , 2007Liu et al 2005;Su et al 2011) and Hinode observations (Jing et al 2008;Li et al 2009). Indirect evidence includes the unbalanced flux evolution of the line-of-sight magnetic field , the variation of the sunspot white-light structure in flaring regions (Wang et al 2004a;Deng et al 2005;Liu et al 2005;Chen et al 2007), and the change in the pattern of the penumbral Evershed flow (Deng et al 2011).…”

Section: Introductionsupporting

confidence: 58%

Rapid Changes of Photospheric Magnetic Field After Tether-Cutting Reconnection and Magnetic Implosion

Liu

Deng

et al. 2011

ApJ

View full text Add to dashboard Cite

The rapid, irreversible change of the photospheric magnetic field has been recognized as an important element of the solar flare process. This Letter reports such a rapid change of magnetic fields during the 2011 February 13 M6.6 flare in NOAA AR 11158 that we found from the vector magnetograms of the Helioseismic and Magnetic Imager (HMI) with 12 minute cadence. High-resolution magnetograms of Hinode that are available at ∼−5.5, −1.5, 1.5, and 4 hr relative to the flare maximum are used to reconstruct a three-dimensional coronal magnetic field under the nonlinear force-free field (NLFFF) assumption. UV and hard X-ray images are also used to illuminate the magnetic field evolution and energy release. The rapid change is mainly detected by HMI in a compact region lying in the center of the magnetic sigmoid, where the mean horizontal field strength exhibited a significant increase of 28%. The region lies between the initial strong UV and hard X-ray sources in the chromosphere, which are cospatial with the central feet of the sigmoid according to the NLFFF model. The NLFFF model further shows that strong coronal currents are concentrated immediately above the region, and that, more intriguingly, the coronal current system underwent an apparent downward collapse after the sigmoid eruption. These results are discussed in favor of both the tether-cutting reconnection producing the flare and the ensuing implosion of the coronal field resulting from the energy release.

show abstract

“…That the magnetic field can be strongly perturbed during a solar flare is not in question: there are many observations of changes to both the line-of-sight and horizontal magnetic field at the photosphere at the time of the flare impulsive phase (e.g. Sudol and Harvey 2005;Wang and Liu 2010;Su et al 2011;Wang et al 2012). A broader question is what effect such perturbations, which are presumed to be driven by magnetic rearrangement in the corona, could have on the flare atmosphere.…”

Section: Introductionmentioning

confidence: 99%

Propagation of Alfvénic Waves From Corona to Chromosphere and Consequences for Solar Flares

Russell

Fletcher

2013

ApJ

View full text Add to dashboard Cite

How do magnetohydrodynamic waves travel from the fully ionized corona, into and through the underlying partially ionized chromosphere, and what are the consequences for solar flares? To address these questions, we have developed a 2-fluid model (of plasma and neutrals) and used it to perform 1D simulations of Alfvén waves in a solar atmosphere with realistic density and temperature structure. Studies of a range of solar features (faculae, plage, penumbra and umbra) show that energy transmission from corona to chromosphere can exceed 20% of incident energy for wave periods of one second or less. Damping of waves in the chromosphere depends strongly on wave frequency: waves with periods 10 seconds or longer pass through the chromosphere with relatively little damping, however, for periods of 1 second or less, a substantial fraction (37%-100%) of wave energy entering the chromosphere is damped by ion-neutral friction in the mid and upper chromosphere, with electron resistivity playing some role in the lower chromosphere and in umbras. We therefore conclude that Alfvénic waves with periods of a few seconds or less are capable of heating the chromosphere during solar flares, and speculate that they could also contribute to electron acceleration or exciting sunquakes.

show abstract

Observational Evidence of Changing Photospheric Vector Magnetic Fields Associated With Solar Flares

Cited by 18 publications

References 32 publications

On the Relationship Between Sunspot Structure and Magnetic Field Changes Associated With Solar Flares

On the Relationship Between Sunspot Structure and Magnetic Field Changes Associated With Solar Flares

Rapid Changes of Photospheric Magnetic Field After Tether-Cutting Reconnection and Magnetic Implosion

Propagation of Alfvénic Waves From Corona to Chromosphere and Consequences for Solar Flares

Contact Info

Product

Resources

About