Non-LTE Calculations of the Fe i 6173 Å Line in a Flaring Atmosphere

Hong, Jie; Ding, M. D.; Li, Ying; Carlsson, Mats

doi:10.3847/2041-8213/aab9aa

Cited by 21 publications

(29 citation statements)

References 34 publications

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“…The measured magnetic field strength then decreases at an early period since the flare heating increases the formation height of the line. Such a result is similar to other lines that are used for magnetic field measurement, including the Ni I 6768 Å line (Ding et al 2002), and the Fe I 6173 Å line (Hong et al 2018).…”

Section: Magnetic Field Inversionsupporting

confidence: 81%

“…The height where τ = 1 is about 360 km for the line center, and 200 km for the absorption trough. The formation height of the absorption trough is somehow similar to that of the Fe I 6173 Å line center (Hong et al 2018). The line source function is defined as…”

Section: Model F10mentioning

confidence: 99%

“…Previous studies have suggested that major solar flares can have large influences on the photospheric lines (Ding et al 2002;Hong et al 2018). However, there are very few observations of a solar flare using the Mg I 12.32 µm line.…”

Section: Introductionmentioning

confidence: 99%

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Non-LTE Calculations of the Mg i 12.32 μm Line in a Flaring Atmosphere

Hong

Bai

Liu

et al. 2020

ApJ

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The infrared Mg I lines near 12 microns are a pair of emission lines which are magnetically sensitive and have been used to measure solar magnetic fields. Here we calculate the response of the Mg I 12.32 µm line during a flare and find that in our modeling this line has a complicated behavior. At the beginning of the flare heating, this line shows an intensity dimming at the line center. The intensity then increases when heating continues, with increasing contributions from the heated layers in the chromosphere. The line formation height and the line width also increase as a result. As for the polarized line profiles, we find that flare heating tends to decrease the Zeeman splitting width and attenuates the Stokes V lobe intensity. The wider features in the Stokes V profiles are more pronounced during flare heating, which should be considered when performing magnetic field inversions.

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Section: Magnetic Field Inversionsupporting

confidence: 81%

Section: Model F10mentioning

confidence: 99%

See 1 more Smart Citation

Non-LTE Calculations of the Mg i 12.32 μm Line in a Flaring Atmosphere

Hong

Bai

Liu

et al. 2020

ApJ

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“…Chen et al (1989) [47]. Some study with Stokes parameters of spectral lines can be found (Hong et al(2018) [91]). Due to the distortion of the spectral lines with the variation of solar atmosphere in the solar eruptive process [3], the analysis of relevant Stokes parameters of the spectral lines is a notable topic.…”

Section: Discussion For Some New Challenges On Measurements Of Solarmentioning

confidence: 99%

From polarimetry to helicity: Studies of solar magnetic fields at the Huairou Solar Observing Station

Zhang¹

2019

Sci. China Phys. Mech. Astron.

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In this paper, we briefly introduce the basic questions in the measurements of solar magnetic fields and the possible error sources due to the approximation of the theory of radiation transfer of spectral lines in the solar atmosphere. We introduce some basic research progress in magnetic field measurement at Huairou Solar Observing Station of National Astronomical Observatories of the Chinese Academy of Sciences, especially concerning the non-potentiality in solar active regions, such as the magnetic shear, current and helicity. We also discuss some basic questions for the measurements of the magnetic fields and corresponding challenges for the future studies. Solar spectrum, Polarization -Stokes parameters, Magnetic fields -current and helicity PACS number(s): Citation: Hongqi Zhang, From Polarimetry to Helicity, Sci. China-Phys. Mech. Astron. , (), doi:

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“…Non-LTE9 modeling by Hong et al. (2018) explained the profile changes of Fe I 6173 Å line that the HMI uses and provided a quantitative assessment of magnetic transients. Song et al.…”

Section: Rapid Changes Of Magnetic Fields Associated With Flaresmentioning

confidence: 99%

Flare-productive active regions

Toriumi

Wang

2019

Living Rev Sol Phys

232

151

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Strong solar flares and coronal mass ejections, here defined not only as the bursts of electromagnetic radiation but as the entire process in which magnetic energy is released through magnetic reconnection and plasma instability, emanate from active regions (ARs) in which high magnetic non-potentiality resides in a wide variety of forms. This review focuses on the formation and evolution of flare-productive ARs from both observational and theoretical points of view. Starting from a general introduction of the genesis of ARs and solar flares, we give an overview of the key observational features during the long-term evolution in the pre-flare state, the rapid changes in the magnetic field associated with the flare occurrence, and the physical mechanisms behind these phenomena. Our picture of flare-productive ARs is summarized as follows: subject to the turbulent convection, the rising magnetic flux in the interior deforms into a complex structure and gains high non-potentiality; as the flux appears on the surface, an AR with large free magnetic energy and helicity is built, which is represented by -sunspots, sheared polarity inversion lines, magnetic flux ropes, etc; the flare occurs when sufficient magnetic energy has accumulated, and the drastic coronal evolution affects magnetic fields even in the photosphere. We show that the improvement of observational instruments and modeling capabilities has significantly advanced our understanding in the last decades. Finally, we discuss the outstanding issues and future perspective and further broaden our scope to the possible applications of our knowledge to space-weather forecasting, extreme events in history, and corresponding stellar activities. Electronic supplementary material The online version of this article (10.1007/s41116-019-0019-7) contains supplementary material, which is available to authorized users.

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Non-LTE Calculations of the Fe i 6173 Å Line in a Flaring Atmosphere

Cited by 21 publications

References 34 publications

Non-LTE Calculations of the Mg i 12.32 μm Line in a Flaring Atmosphere

Non-LTE Calculations of the Mg i 12.32 μm Line in a Flaring Atmosphere

From polarimetry to helicity: Studies of solar magnetic fields at the Huairou Solar Observing Station

Flare-productive active regions

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