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Title: NUMERICAL SIMULATIONS OF HELICITY CONDENSATION IN THE SOLAR CORONA

Abstract

The helicity condensation model has been proposed by Antiochos to explain the observed smoothness of coronal loops and the observed buildup of magnetic shear at filament channels. The basic hypothesis of the model is that magnetic reconnection in the corona causes the magnetic stress injected by photospheric motions to collect only at those special locations where prominences are observed to form. In this work we present the first detailed quantitative MHD simulations of the reconnection evolution proposed by the helicity condensation model. We use the well-known ansatz of modeling the closed corona as an initially uniform field between two horizontal photospheric plates. The system is driven by applying photospheric rotational flows that inject magnetic helicity into the corona. The flows are confined to a finite region on the photosphere so as to mimic the finite flux system of a bipolar active region, for example. The calculations demonstrate that, contrary to common belief, opposite helicity twists do not lead to significant reconnection in such a coronal system, whereas twists with the same sense of helicity do produce substantial reconnection. Furthermore, we find that for a given amount of helicity injected into the corona, the evolution of the magnetic shear is insensitivemore » to whether the pattern of driving photospheric motions is fixed or quasi-random. In all cases, the shear propagates via reconnection to the boundary of the flow region while the total magnetic helicity is conserved, as predicted by the model. We discuss the implications of our results for solar observations and for future, more realistic simulations of the helicity condensation process.« less

Authors:
;  [1]; ;  [2]
  1. Department of Atmospheric, Oceanic, and Space Sciences, University of Michigan, Ann Arbor, MI 48105 (United States)
  2. Heliophysics Science Division, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)
Publication Date:
OSTI Identifier:
22522195
Resource Type:
Journal Article
Journal Name:
Astrophysical Journal
Additional Journal Information:
Journal Volume: 805; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0004-637X
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; COMPUTERIZED SIMULATION; FILAMENTS; HELICITY; MAGNETIC FIELDS; MAGNETIC RECONNECTION; MAGNETOHYDRODYNAMICS; PHOTOSPHERE; RANDOMNESS; ROUGHNESS; SHEAR; SOLAR CORONA; SOLAR PROMINENCES; STAR EVOLUTION; STRESSES; SUN

Citation Formats

Zhao, L., Zurbuchen, T. H., DeVore, C. R., and Antiochos, S. K. NUMERICAL SIMULATIONS OF HELICITY CONDENSATION IN THE SOLAR CORONA. United States: N. p., 2015. Web. doi:10.1088/0004-637X/805/1/61.
Zhao, L., Zurbuchen, T. H., DeVore, C. R., & Antiochos, S. K. NUMERICAL SIMULATIONS OF HELICITY CONDENSATION IN THE SOLAR CORONA. United States. doi:10.1088/0004-637X/805/1/61.
Zhao, L., Zurbuchen, T. H., DeVore, C. R., and Antiochos, S. K. Wed . "NUMERICAL SIMULATIONS OF HELICITY CONDENSATION IN THE SOLAR CORONA". United States. doi:10.1088/0004-637X/805/1/61.
@article{osti_22522195,
title = {NUMERICAL SIMULATIONS OF HELICITY CONDENSATION IN THE SOLAR CORONA},
author = {Zhao, L. and Zurbuchen, T. H. and DeVore, C. R. and Antiochos, S. K.},
abstractNote = {The helicity condensation model has been proposed by Antiochos to explain the observed smoothness of coronal loops and the observed buildup of magnetic shear at filament channels. The basic hypothesis of the model is that magnetic reconnection in the corona causes the magnetic stress injected by photospheric motions to collect only at those special locations where prominences are observed to form. In this work we present the first detailed quantitative MHD simulations of the reconnection evolution proposed by the helicity condensation model. We use the well-known ansatz of modeling the closed corona as an initially uniform field between two horizontal photospheric plates. The system is driven by applying photospheric rotational flows that inject magnetic helicity into the corona. The flows are confined to a finite region on the photosphere so as to mimic the finite flux system of a bipolar active region, for example. The calculations demonstrate that, contrary to common belief, opposite helicity twists do not lead to significant reconnection in such a coronal system, whereas twists with the same sense of helicity do produce substantial reconnection. Furthermore, we find that for a given amount of helicity injected into the corona, the evolution of the magnetic shear is insensitive to whether the pattern of driving photospheric motions is fixed or quasi-random. In all cases, the shear propagates via reconnection to the boundary of the flow region while the total magnetic helicity is conserved, as predicted by the model. We discuss the implications of our results for solar observations and for future, more realistic simulations of the helicity condensation process.},
doi = {10.1088/0004-637X/805/1/61},
journal = {Astrophysical Journal},
issn = {0004-637X},
number = 1,
volume = 805,
place = {United States},
year = {2015},
month = {5}
}