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Title: EVOLUTION OF RELATIVE MAGNETIC HELICITY AND CURRENT HELICITY IN NOAA ACTIVE REGION 11158

Abstract

Both magnetic and current helicities are crucial ingredients for describing the complexity of active-region magnetic structure. In this Letter, we present the temporal evolution of these helicities contained in NOAA active region 11158 during five days from 2011 February 12 to 16. The photospheric vector magnetograms of the Helioseismic and Magnetic Imager on board the Solar Dynamic Observatory were used as the boundary conditions for the coronal field extrapolation under the assumption of nonlinear force-free field, from which we calculated both relative magnetic helicity and current helicity. We construct a time-altitude diagram in which altitude distribution of the magnitude of current helicity density is displayed as a function of time. This diagram clearly shows a pattern of upwardly propagating current helicity density over two days prior to the X2.2 flare on February 15 with an average propagation speed of {approx}36 m s{sup -1}. The propagation is synchronous with the emergence of magnetic flux into the photosphere, and indicative of a gradual energy buildup for the X2.2 flare. The time profile of the relative magnetic helicity shows a monotonically increasing trend most of the time, but a pattern of increasing and decreasing magnetic helicity above the monotonic variation appears prior tomore » each of two major flares, M6.6 and X2.2, respectively. The physics underlying this bump pattern is not fully understood. However, the fact that this pattern is apparent in the magnetic helicity evolution but not in the magnetic flux evolution makes it a useful indicator in forecasting major flares.« less

Authors:
; ; ; ; ;  [1];  [2];  [3]
  1. Space Weather Research Laboratory, New Jersey Institute of Technology, Newark, NJ 07102 (United States)
  2. Korea Astronomy and Space Science Institute, Daejeon, 305-348 (Korea, Republic of)
  3. Max Planck Institut fuer Sonnensystemforschung (MPS), Max-Planck-Strasse 2, 37191 Katlenburg-Lindau (Germany)
Publication Date:
OSTI Identifier:
22047767
Resource Type:
Journal Article
Journal Name:
Astrophysical Journal Letters
Additional Journal Information:
Journal Volume: 752; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 2041-8205
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ASTROPHYSICS; BOUNDARY CONDITIONS; DENSITY; DIAGRAMS; EVOLUTION; HELICITY; MAGNETIC FLUX; MAGNETISM; NONLINEAR PROBLEMS; PHOTOSPHERE; SOLAR FLARES; SUN; TIME DEPENDENCE; VELOCITY

Citation Formats

Jing, Ju, Liu, Chang, Lee, Jeongwoo, Xu, Yan, Deng, Na, Wang, Haimin, Park, Sung-Hong, and Wiegelmann, Thomas, E-mail: ju.jing@njit.edu, E-mail: chang.liu@njit.edu, E-mail: yx2@njit.edu, E-mail: na.deng@njit.edu, E-mail: haimin@flare.njit.edu, E-mail: freemler@kasi.re.kr, E-mail: leej@njit.edu, E-mail: wiegelmann@linmpi.mpg.de. EVOLUTION OF RELATIVE MAGNETIC HELICITY AND CURRENT HELICITY IN NOAA ACTIVE REGION 11158. United States: N. p., 2012. Web. doi:10.1088/2041-8205/752/1/L9.
Jing, Ju, Liu, Chang, Lee, Jeongwoo, Xu, Yan, Deng, Na, Wang, Haimin, Park, Sung-Hong, & Wiegelmann, Thomas, E-mail: ju.jing@njit.edu, E-mail: chang.liu@njit.edu, E-mail: yx2@njit.edu, E-mail: na.deng@njit.edu, E-mail: haimin@flare.njit.edu, E-mail: freemler@kasi.re.kr, E-mail: leej@njit.edu, E-mail: wiegelmann@linmpi.mpg.de. EVOLUTION OF RELATIVE MAGNETIC HELICITY AND CURRENT HELICITY IN NOAA ACTIVE REGION 11158. United States. doi:10.1088/2041-8205/752/1/L9.
Jing, Ju, Liu, Chang, Lee, Jeongwoo, Xu, Yan, Deng, Na, Wang, Haimin, Park, Sung-Hong, and Wiegelmann, Thomas, E-mail: ju.jing@njit.edu, E-mail: chang.liu@njit.edu, E-mail: yx2@njit.edu, E-mail: na.deng@njit.edu, E-mail: haimin@flare.njit.edu, E-mail: freemler@kasi.re.kr, E-mail: leej@njit.edu, E-mail: wiegelmann@linmpi.mpg.de. Sun . "EVOLUTION OF RELATIVE MAGNETIC HELICITY AND CURRENT HELICITY IN NOAA ACTIVE REGION 11158". United States. doi:10.1088/2041-8205/752/1/L9.
@article{osti_22047767,
title = {EVOLUTION OF RELATIVE MAGNETIC HELICITY AND CURRENT HELICITY IN NOAA ACTIVE REGION 11158},
author = {Jing, Ju and Liu, Chang and Lee, Jeongwoo and Xu, Yan and Deng, Na and Wang, Haimin and Park, Sung-Hong and Wiegelmann, Thomas, E-mail: ju.jing@njit.edu, E-mail: chang.liu@njit.edu, E-mail: yx2@njit.edu, E-mail: na.deng@njit.edu, E-mail: haimin@flare.njit.edu, E-mail: freemler@kasi.re.kr, E-mail: leej@njit.edu, E-mail: wiegelmann@linmpi.mpg.de},
abstractNote = {Both magnetic and current helicities are crucial ingredients for describing the complexity of active-region magnetic structure. In this Letter, we present the temporal evolution of these helicities contained in NOAA active region 11158 during five days from 2011 February 12 to 16. The photospheric vector magnetograms of the Helioseismic and Magnetic Imager on board the Solar Dynamic Observatory were used as the boundary conditions for the coronal field extrapolation under the assumption of nonlinear force-free field, from which we calculated both relative magnetic helicity and current helicity. We construct a time-altitude diagram in which altitude distribution of the magnitude of current helicity density is displayed as a function of time. This diagram clearly shows a pattern of upwardly propagating current helicity density over two days prior to the X2.2 flare on February 15 with an average propagation speed of {approx}36 m s{sup -1}. The propagation is synchronous with the emergence of magnetic flux into the photosphere, and indicative of a gradual energy buildup for the X2.2 flare. The time profile of the relative magnetic helicity shows a monotonically increasing trend most of the time, but a pattern of increasing and decreasing magnetic helicity above the monotonic variation appears prior to each of two major flares, M6.6 and X2.2, respectively. The physics underlying this bump pattern is not fully understood. However, the fact that this pattern is apparent in the magnetic helicity evolution but not in the magnetic flux evolution makes it a useful indicator in forecasting major flares.},
doi = {10.1088/2041-8205/752/1/L9},
journal = {Astrophysical Journal Letters},
issn = {2041-8205},
number = 1,
volume = 752,
place = {United States},
year = {2012},
month = {6}
}