Magnetic structure and nonthermal electrons in the X6.9 flare on 2011 August 9

Jung Eun Hwangbo, Jeongwoo Lee, Sung Hong Park, Sujin Kim, Dae Young Lee, Su Chan Bong, Yeon Han Kim, Kyung Suk Cho, Young Deuk Park

Research output: Contribution to journalArticlepeer-review

3 Scopus citations


The 2011 August 9 flare is one of the largest X-ray flares of sunspot cycle 24, but spatial information is rather limited due to its position close to the western limb. This paper presents information about the location of high-energy electrons derived from hard X-ray and microwave spectra obtained with the Reuven Ramaty High-Energy Solar Spectroscopic Imager (RHESSI) and the Korean Solar Radio Burst Locator (KSRBL), respectively. The KSRBL microwave spectrum shows significant fluxes at low frequencies, implying that the high-energy electrons reside in a coronal volume highly concentrated at strong magnetic fields, and rapidly expanding with decreasing magnetic fields. After a simple modeling of the microwave spectrum, we found that the microwave source should be located above the inner pair of magnetic poles in a large quadrupolar configuration. The time-dependent evolution of the magnetic field distribution and total nonthermal energy derived from the microwave spectra is also consistent with the standard picture of multiple magnetic reconnections recurring at a magnetic null point that forms above the magnetic quadrupoles and moves up with time.

Original languageEnglish (US)
Article number80
JournalAstrophysical Journal
Issue number2
StatePublished - Dec 1 2014

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


  • Sun: X-rays, gamma rays
  • Sun: flares
  • Sun: magnetic fields
  • Sun: radio radiation
  • magnetic reconnection


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