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Title: NON-THERMAL RESPONSE OF THE CORONA TO THE MAGNETIC FLUX DISPERSAL IN THE PHOTOSPHERE OF A DECAYING ACTIVE REGION

Abstract

We analyzed Solar Dynamics Observatory line-of-sight magnetograms for a decaying NOAA active region (AR) 11451 along with co-temporal Extreme-Ultraviolet Imaging Spectrometer (EIS) data from the Hinode spacecraft. The photosphere was studied via time variations of the turbulent magnetic diffusivity coefficient, {eta}(t), and the magnetic power spectrum index, {alpha}, through analysis of magnetogram data from the Helioseismic and Magnetic Imager (HMI). These measure the intensity of the random motions of magnetic elements and the state of turbulence of the magnetic field, respectively. The time changes of the non-thermal energy release in the corona was explored via histogram analysis of the non-thermal velocity, v {sub nt}, in order to highlight the largest values at each time, which may indicate an increase in energy release in the corona. We used the 10% upper range of the histogram of v {sub nt} (which we called V {sup upp} {sub nt}) of the coronal spectral line of Fe XII 195 A. A 2 day time interval was analyzed from HMI data, along with the EIS data for the same field of view. Our main findings are the following. (1) The magnetic turbulent diffusion coefficient, {eta}(t), precedes the upper range of the v {sub nt} withmore » the time lag of approximately 2 hr and the cross-correlation coefficient of 0.76. (2) The power-law index, {alpha}, of the magnetic power spectrum precedes V {sup upp} {sub nt} with a time lag of approximately 3 hr and the cross-correlation coefficient of 0.5. The data show that the magnetic flux dispersal in the photosphere is relevant to non-thermal energy release dynamics in the above corona. The results are consistent with the nanoflare mechanism of the coronal heating, due to the time lags being consistent with the process of heating and cooling the loops heated by nanoflares.« less

Authors:
 [1];  [2]
  1. UCL-Mullard Space Science Laboratory, Holmbury St. Mary, Dorking, Surrey, RH5 6NT (United Kingdom)
  2. Big Bear Solar Observatory, 40386 N. Shore Lane, Big Bear City, CA 92314 (United States)
Publication Date:
OSTI Identifier:
22086408
Resource Type:
Journal Article
Journal Name:
Astrophysical Journal
Additional Journal Information:
Journal Volume: 759; Journal Issue: 2; 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; ASTRONOMY; ASTROPHYSICS; COOLING; CORRELATIONS; DIFFUSION; ENERGY SPECTRA; EXTREME ULTRAVIOLET RADIATION; HEATING; INDEXES; MAGNETIC FIELDS; MAGNETIC FLUX; MAGNETISM; PHOTOSPHERE; RANDOMNESS; SOLAR CORONA; SUN; TURBULENCE

Citation Formats

Harra, L. K., and Abramenko, V. I. NON-THERMAL RESPONSE OF THE CORONA TO THE MAGNETIC FLUX DISPERSAL IN THE PHOTOSPHERE OF A DECAYING ACTIVE REGION. United States: N. p., 2012. Web. doi:10.1088/0004-637X/759/2/104.
Harra, L. K., & Abramenko, V. I. NON-THERMAL RESPONSE OF THE CORONA TO THE MAGNETIC FLUX DISPERSAL IN THE PHOTOSPHERE OF A DECAYING ACTIVE REGION. United States. doi:10.1088/0004-637X/759/2/104.
Harra, L. K., and Abramenko, V. I. Sat . "NON-THERMAL RESPONSE OF THE CORONA TO THE MAGNETIC FLUX DISPERSAL IN THE PHOTOSPHERE OF A DECAYING ACTIVE REGION". United States. doi:10.1088/0004-637X/759/2/104.
@article{osti_22086408,
title = {NON-THERMAL RESPONSE OF THE CORONA TO THE MAGNETIC FLUX DISPERSAL IN THE PHOTOSPHERE OF A DECAYING ACTIVE REGION},
author = {Harra, L. K. and Abramenko, V. I.},
abstractNote = {We analyzed Solar Dynamics Observatory line-of-sight magnetograms for a decaying NOAA active region (AR) 11451 along with co-temporal Extreme-Ultraviolet Imaging Spectrometer (EIS) data from the Hinode spacecraft. The photosphere was studied via time variations of the turbulent magnetic diffusivity coefficient, {eta}(t), and the magnetic power spectrum index, {alpha}, through analysis of magnetogram data from the Helioseismic and Magnetic Imager (HMI). These measure the intensity of the random motions of magnetic elements and the state of turbulence of the magnetic field, respectively. The time changes of the non-thermal energy release in the corona was explored via histogram analysis of the non-thermal velocity, v {sub nt}, in order to highlight the largest values at each time, which may indicate an increase in energy release in the corona. We used the 10% upper range of the histogram of v {sub nt} (which we called V {sup upp} {sub nt}) of the coronal spectral line of Fe XII 195 A. A 2 day time interval was analyzed from HMI data, along with the EIS data for the same field of view. Our main findings are the following. (1) The magnetic turbulent diffusion coefficient, {eta}(t), precedes the upper range of the v {sub nt} with the time lag of approximately 2 hr and the cross-correlation coefficient of 0.76. (2) The power-law index, {alpha}, of the magnetic power spectrum precedes V {sup upp} {sub nt} with a time lag of approximately 3 hr and the cross-correlation coefficient of 0.5. The data show that the magnetic flux dispersal in the photosphere is relevant to non-thermal energy release dynamics in the above corona. The results are consistent with the nanoflare mechanism of the coronal heating, due to the time lags being consistent with the process of heating and cooling the loops heated by nanoflares.},
doi = {10.1088/0004-637X/759/2/104},
journal = {Astrophysical Journal},
issn = {0004-637X},
number = 2,
volume = 759,
place = {United States},
year = {2012},
month = {11}
}