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Title: OBSERVING CORONAL NANOFLARES IN ACTIVE REGION MOSS

The High-resolution Coronal Imager (Hi-C) has provided Fe XII 193A images of the upper transition region moss at an unprecedented spatial ({approx}0.''3-0.''4) and temporal (5.5 s) resolution. The Hi-C observations show in some moss regions variability on timescales down to {approx}15 s, significantly shorter than the minute-scale variability typically found in previous observations of moss, therefore challenging the conclusion of moss being heated in a mostly steady manner. These rapid variability moss regions are located at the footpoints of bright hot coronal loops observed by the Solar Dynamics Observatory/Atmospheric Imaging Assembly in the 94 A channel, and by the Hinode/X-Ray Telescope. The configuration of these loops is highly dynamic, and suggestive of slipping reconnection. We interpret these events as signatures of heating events associated with reconnection occurring in the overlying hot coronal loops, i.e., coronal nanoflares. We estimate the order of magnitude of the energy in these events to be of at least a few 10{sup 23} erg, also supporting the nanoflare scenario. These Hi-C observations suggest that future observations at comparable high spatial and temporal resolution, with more extensive temperature coverage, are required to determine the exact characteristics of the heating mechanism(s).
Authors:
; ; ; ;  [1] ; ; ;  [2] ;  [3] ; ; ;  [4] ;  [5] ;  [6] ;  [7]
  1. Smithsonian Astrophysical Observatory, 60 Garden street, MS 58, Cambridge, MA 02138 (United States)
  2. Lockheed Martin Solar and Astrophysics Lab, Org. A021S, Bldg. 252, 3251 Hanover Street, Palo Alto, CA 94304 (United States)
  3. Institute of Theoretical Astrophysics, University of Oslo, P.O. Box 1029 Blindern, N-0315 Oslo (Norway)
  4. NASA Marshall Space Flight Center, ZP 13, Huntsville, AL 35812 (United States)
  5. P. N. Lebedev Physical institute of the Russian Academy of Sciences, Leninskii prospekt, 53, 119991 Moscow (Russian Federation)
  6. University of Central Lancashire, Lancashire, Preston PR1 2HE (United Kingdom)
  7. Southwest Research Institute, 1050 Walnut Street, Suite 300, Boulder, CO 80302 (United States)
Publication Date:
OSTI Identifier:
22118801
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal Letters; Journal Volume: 770; 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; ASTRONOMY; ASTROPHYSICS; COMPARATIVE EVALUATIONS; HEATING; IMAGES; IRON IONS; SOLAR CORONA; SOLAR FLARES; SPATIAL RESOLUTION; SUN; TIME RESOLUTION; ULTRAVIOLET RADIATION; X RADIATION