Three-dimensional magnetic restructuring in two homologous solar flares in the seismically active NOAA AR 11283

Chang Liu, Na Deng, Jeongwoo Lee, Thomas Wiegelmann, Chaowei Jiang, Brian R. Dennis, Yang Su, Alina Donea, Haimin Wang

Research output: Contribution to journalArticlepeer-review

28 Scopus citations

Abstract

We carry out a comprehensive investigation comparing the three-dimensional magnetic field restructuring, flare energy release, and the helioseismic response of two homologous flares, the 2011 September 6 X2.1 (FL1) and September 7 X1.8 (FL2) flares in NOAA AR 11283. In our analysis, (1) a twisted flux rope (FR) collapses onto the surface at a speed of 1.5 km s-1 after a partial eruption in FL1. The FR then gradually grows to reach a higher altitude and collapses again at 3 km s-1 after a fuller eruption in FL2. Also, FL2 shows a larger decrease of the flux-weighted centroid separation of opposite magnetic polarities and a greater change of the horizontal field on the surface. These imply a more violent coronal implosion with corresponding more intense surface signatures in FL2. (2) The FR is inclined northward and together with the ambient fields, it undergoes a southward turning after both events. This agrees with the asymmetric decay of the penumbra observed in the peripheral regions. (3) The amounts of free magnetic energy and nonthermal electron energy released during FL1 are comparable to those of FL2 within the uncertainties of the measurements. (4) No sunquake was detected in FL1; in contrast, FL2 produced two seismic emission sources S1 and S2 both lying in the penumbral regions. Interestingly, S1 and S2 are connected by magnetic loops, and the stronger source S2 has a weaker vertical magnetic field. We discuss these results in relation to the implosion process in the low corona and the sunquake generation.

Original languageEnglish (US)
Article number128
JournalAstrophysical Journal
Volume795
Issue number2
DOIs
StatePublished - Nov 10 2014

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

Keywords

  • Sun: X-rays, gamma rays
  • Sun: activity
  • Sun: flares
  • Sun: helioseismology
  • Sun: magnetic fields

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