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Title: A STUDY OF FAST FLARELESS CORONAL MASS EJECTIONS

Two major processes have been proposed to convert coronal magnetic energy into the kinetic energy of a coronal mass ejection (CME): resistive magnetic reconnection and the ideal macroscopic magnetohydrodynamic instability of a magnetic flux rope. However, it remains elusive whether both processes play a comparable role or one of them prevails during a particular eruption. To shed light on this issue, we carefully studied energetic but flareless CMEs, i.e., fast CMEs not accompanied by any flares. Through searching the Coordinated Data Analysis Workshops database of CMEs observed in Solar Cycle 23, we found 13 such events with speeds larger than 1000 km s{sup -1}. Other common observational features of these events are: (1) none of them originated in active regions, they were associated with eruptions of well-developed long filaments in quiet-Sun regions; (2) no apparent enhancement of flare emissions was present in soft X-ray, EUV, and microwave data. Further studies of two events reveal that (1) the reconnection electric fields, as inferred from the product of the separation speed of post-eruption ribbons and the photospheric magnetic field measurement, were generally weak; (2) the period with a measurable reconnection electric field is considerably shorter than the total filament-CME acceleration time. Thesemore » observations indicate that for these fast CMEs, the magnetic energy was released mainly via the ideal flux-rope instability through the work done by the large-scale Lorentz force acting on the rope currents rather than via magnetic reconnections. We also suggest that reconnections play a less important role in accelerating CMEs in quiet-Sun regions of weak magnetic field than those in active regions of strong magnetic field.« less
Authors:
; ; ; ; ;  [1] ;  [2] ;  [3]
  1. Institute of Space Sciences and School of Space Science and Physics, Shandong University, Weihai, Shandong 264209 (China)
  2. School of Physics, Astronomy and Computational Sciences, George Mason University, Fairfax, VA 22030 (United States)
  3. Department of Physics and CSPAR, University of Alabama in Huntsville, Huntsville, AL 35899 (United States)
Publication Date:
OSTI Identifier:
22130982
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 773; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; DATA ANALYSIS; ELECTRIC FIELDS; EMISSION; ERUPTION; EXTREME ULTRAVIOLET RADIATION; KINETIC ENERGY; LORENTZ FORCE; MAGNETIC FIELDS; MAGNETIC FLUX; MAGNETIC RECONNECTION; MICROWAVE RADIATION; SOFT X RADIATION; SOLAR CYCLE; SOLAR FLARES; SUN