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Title: Quasi-periodic pulsations with varying period in multi-wavelength observations of an X-class flare

This work presents an interesting phenomenon of the period variation in quasi-periodic pulsations (QPPs) observed during the impulsive phase of a coronal mass ejection-related X1.1 class flare on 2012 July 6. The period of QPPs was changed from 21 s at soft X-rays (SXR) to 22-23 s at microwaves, to ∼24 s at extreme ultraviolet emissions (EUV), and to 27-32 s at metric-decimetric waves. The microwave, EUV, and SXR QPPs, emitted from flare loops of different heights, were oscillating in phase. Fast kink mode oscillations were proposed to be the modulation mechanism, which may exist in a wide region in the solar atmosphere from the chromosphere to the upper corona or even to the interplanetary space. Changed parameters of flare loops through the solar atmosphere could result in the varying period of QPPs at different wavelengths. The first appearing microwave QPPs and quasi-periodic metric-decimetric type III bursts were generated by energetic electrons. This may imply that particle acceleration or magnetic reconnection were located between these two non-thermal emission sources. Thermal QPPs (in SXR and EUV emissions) occurred later than the nonthermal ones, which would suggest a some time for plasma heating or energy dissipation in flare loops during burst processes.more » At the beginning of flare, a sudden collapse and expansion of two separated flare loop structures occurred simultaneously with the multi-wavelength QPPs. An implosion in the corona, including both collapse and expansion of flare loops, could be a trigger of loop oscillations in a very large region in the solar atmosphere.« less
Authors:
; ;  [1] ; ;  [2]
  1. Key Laboratory of Solar Activities, National Astronomical Observatories Chinese Academy of Sciences, Beijing 100012 (China)
  2. Astronomical Institute of the Academy of Sciences of the Czech Republic, CZ-25165 Ondřejov (Czech Republic)
Publication Date:
OSTI Identifier:
22365391
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 791; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ACCELERATION; CHROMOSPHERE; EMISSION; ENERGY LOSSES; EXPANSION; EXTREME ULTRAVIOLET RADIATION; INTERPLANETARY SPACE; MAGNETIC RECONNECTION; MASS; MICROWAVE RADIATION; MODULATION; OSCILLATION MODES; OSCILLATIONS; PERIODICITY; PLASMA HEATING; PULSATIONS; SOFT X RADIATION; SUN; WAVELENGTHS