CORONAL MAGNETIC FIELDS DERIVED FROM SIMULTANEOUS MICROWAVE AND EUV OBSERVATIONS AND COMPARISON WITH THE POTENTIAL FIELD MODEL

Miyawaki, Shun; Nozawa, Satoshi; Iwai, Kazumasa; Shibasaki, Kiyoto; Shiota, Daikou

doi:10.3847/0004-637X/818/1/8

Title: CORONAL MAGNETIC FIELDS DERIVED FROM SIMULTANEOUS MICROWAVE AND EUV OBSERVATIONS AND COMPARISON WITH THE POTENTIAL FIELD MODEL

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Abstract

We estimated the accuracy of coronal magnetic fields derived from radio observations by comparing them to potential field calculations and the differential emission measure measurements using EUV observations. We derived line-of-sight components of the coronal magnetic field from polarization observations of the thermal bremsstrahlung in the NOAA active region 11150, observed around 3:00 UT on 2011 February 3 using the Nobeyama Radioheliograph at 17 GHz. Because the thermal bremsstrahlung intensity at 17 GHz includes both chromospheric and coronal components, we extracted only the coronal component by measuring the coronal emission measure in EUV observations. In addition, we derived only the radio polarization component of the corona by selecting the region of coronal loops and weak magnetic field strength in the chromosphere along the line of sight. The upper limits of the coronal longitudinal magnetic fields were determined as 100–210 G. We also calculated the coronal longitudinal magnetic fields from the potential field extrapolation using the photospheric magnetic field obtained from the Helioseismic and Magnetic Imager. However, the calculated potential fields were certainly smaller than the observed coronal longitudinal magnetic field. This discrepancy between the potential and the observed magnetic field strengths can be explained consistently by two reasons: (1) the underestimationmore »« less

Authors:

Miyawaki, Shun; Nozawa, Satoshi ^[1]; Iwai, Kazumasa; Shibasaki, Kiyoto ^[2]; Shiota, Daikou ^[3]

Department of Science, Ibaraki University, Mito, Ibaraki 310-8512 (Japan)
Nobeyama Solar Radio Observatory, National Astronomical Observatory of Japan, Minamimaki, Nagano 384-1305 (Japan)
Solar-Terrestrial Environment Laboratory, Nagoya University, Nagoya, Aichi 464-8601 (Japan)

Publication Date:: Wed Feb 10 00:00:00 EST 2016

OSTI Identifier:: 22521600

Resource Type:: Journal Article

Journal Name:: Astrophysical Journal

Additional Journal Information:: Journal Volume: 818; 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; BREMSSTRAHLUNG; CHROMOSPHERE; COMPARATIVE EVALUATIONS; EXTRAPOLATION; EXTREME ULTRAVIOLET RADIATION; GHZ RANGE; MAGNETIC FIELDS; MICROWAVE RADIATION; POLARIZATION; SOLAR CORONA; SUN

Citation Formats


                    Miyawaki, Shun, Nozawa, Satoshi, Iwai, Kazumasa, Shibasaki, Kiyoto, and Shiota, Daikou. CORONAL MAGNETIC FIELDS DERIVED FROM SIMULTANEOUS MICROWAVE AND EUV OBSERVATIONS AND COMPARISON WITH THE POTENTIAL FIELD MODEL.  United States: N. p., 2016. 
        Web.  doi:10.3847/0004-637X/818/1/8.

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                    Miyawaki, Shun, Nozawa, Satoshi, Iwai, Kazumasa, Shibasaki, Kiyoto, & Shiota, Daikou. CORONAL MAGNETIC FIELDS DERIVED FROM SIMULTANEOUS MICROWAVE AND EUV OBSERVATIONS AND COMPARISON WITH THE POTENTIAL FIELD MODEL.  United States.  https://doi.org/10.3847/0004-637X/818/1/8

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                    Miyawaki, Shun, Nozawa, Satoshi, Iwai, Kazumasa, Shibasaki, Kiyoto, and Shiota, Daikou. 2016.  
        "CORONAL MAGNETIC FIELDS DERIVED FROM SIMULTANEOUS MICROWAVE AND EUV OBSERVATIONS AND COMPARISON WITH THE POTENTIAL FIELD MODEL".  United States.  https://doi.org/10.3847/0004-637X/818/1/8.

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@article{osti_22521600,

  title        = {CORONAL MAGNETIC FIELDS DERIVED FROM SIMULTANEOUS MICROWAVE AND EUV OBSERVATIONS AND COMPARISON WITH THE POTENTIAL FIELD MODEL},

  author       = {Miyawaki, Shun and Nozawa, Satoshi and Iwai, Kazumasa and Shibasaki, Kiyoto and Shiota, Daikou},

  abstractNote = {We estimated the accuracy of coronal magnetic fields derived from radio observations by comparing them to potential field calculations and the differential emission measure measurements using EUV observations. We derived line-of-sight components of the coronal magnetic field from polarization observations of the thermal bremsstrahlung in the NOAA active region 11150, observed around 3:00 UT on 2011 February 3 using the Nobeyama Radioheliograph at 17 GHz. Because the thermal bremsstrahlung intensity at 17 GHz includes both chromospheric and coronal components, we extracted only the coronal component by measuring the coronal emission measure in EUV observations. In addition, we derived only the radio polarization component of the corona by selecting the region of coronal loops and weak magnetic field strength in the chromosphere along the line of sight. The upper limits of the coronal longitudinal magnetic fields were determined as 100–210 G. We also calculated the coronal longitudinal magnetic fields from the potential field extrapolation using the photospheric magnetic field obtained from the Helioseismic and Magnetic Imager. However, the calculated potential fields were certainly smaller than the observed coronal longitudinal magnetic field. This discrepancy between the potential and the observed magnetic field strengths can be explained consistently by two reasons: (1) the underestimation of the coronal emission measure resulting from the limitation of the temperature range of the EUV observations, and (2) the underestimation of the coronal magnetic field resulting from the potential field assumption.},

  doi          = {10.3847/0004-637X/818/1/8},

  url          = {https://www.osti.gov/biblio/22521600},
  journal      = {Astrophysical Journal},

  issn         = {0004-637X},

  number       = 1,

  volume       = 818,

  place        = {United States},

  year         = {Wed Feb 10 00:00:00 EST 2016},

  month        = {Wed Feb 10 00:00:00 EST 2016}

}

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