Magnetohydrostatic modeling of the solar atmosphere

Zhu, Xiaoshuai; Neukirch, T.; Wiegelmann, T.

doi:10.1007/s11431-022-2047-8

Cited by 12 publications

(8 citation statements)

References 119 publications

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“…Recently, Anfinogentov et al (2019) reported that the magnetic field strength at the base of the corona in an active region could reach 4000 Gauss. Radio observations have also been applied to magnetic field measurements in flaring structures (e.g., Tan et al 2016;Gary et al 2018;Chen et al 2020;Zhu et al 2022). For example, Fleishman et al (2020) observed obvious decay of the magnetic field strength during a flare, indicating that the eruption is triggered by magnetic reconnection.…”

Section: Introductionmentioning

confidence: 99%

“…Another approach to determine the coronal magnetic field structures is by using magnetic field extrapolation from photospheric magnetograms taken from observations in an active region (e.g., Sun et al 2012;Aschwanden 2013;Wang et al 2015a;Chifu et al 2017;Zhu & Wiegelmann 2018;Wiegelmann & Sakurai 2021;Zhu et al 2022) or the whole corona (e.g., Schatten et al 1969;Aly 1984;Tadesse et al 2014). In addition, the combination of extreme ultraviolet (EUV) or infrared observations and magnetic-field models (e.g., Liu & Lin 2008;Liu 2009;Li et al 2017;Chen et al 2018;Zhang et al 2022) or magnetohydrodynamic (MHD) models (e.g., Dove et al 2011;Rachmeler et al 2013;Gibson et al 2016;Zhao et al 2021Zhao et al , 2019Jiang et al 2022) can also aid in the understanding of the magnetic field structures in the corona.…”

Section: Introductionmentioning

confidence: 99%

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Application of a Magnetic-field-induced Transition in Fe x to Solar and Stellar Coronal Magnetic Field Measurements

Chen¹,

Li²,

Bai³

et al. 2023

Res. Astron. Astrophys.

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Magnetic fields play a key role in driving a broad range of dynamic phenomena in the atmospheres of the Sun and other stars. Routine and accurate measurements of the magnetic field at all atmospheric layers are of critical importance to understand these magnetic activities but in the solar and stellar coronae they are a challenge. It was recently proposed that the magnetic-field-induced transition (MIT) in Fe~{\sc{x}} can be used to measure the weak coronal magnetic fields. In this review, we present an overview of recent progresses in the application of this method in astrophysics. We start by introducing the theory underlying the MIT method and reviewing the existing atomic data critical for the spectral modeling of Fe~{\sc{x}} lines. We also discuss the laboratory measurements that verify the potential capability of the MIT technique as a probe for diagnosing the plasma magnetic fields. We then continue by investigating the suitability and accuracy of solar and stellar coronal magnetic field measurements based on the MIT method through forward modeling. Furthermore, we discuss application of the MIT method to existing spectroscopic observations taken by the Extreme-ultraviolet Imaging Spectrometer onboard \textit{Hinode}. This novel technique provides a possible solution for routine magnetic field measurements of the solar and stellar coronae but still requires further efforts to achieve accurate measurements. Finally, the challenges and prospects for future research on this topic are discussed.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Application of a Magnetic-field-induced Transition in Fe x to Solar and Stellar Coronal Magnetic Field Measurements

Chen¹,

Li²,

Bai³

et al. 2023

Res. Astron. Astrophys.

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“…Another approach is to construct coronal magnetic field models through extrapolations from magnetic field maps in the photosphere (e.g., Schatten et al 1969;Zhu & Wiegelmann 2018;Wiegelmann & Sakurai 2021;Zhu et al 2022). The combination of magnetic field or magnetohydrodynamic (MHD) models and coronal observations in extreme ultraviolet (EUV) or infrared passbands can also be used to infer the magnetic field structures in the corona (e.g., Liu & Lin 2008;Liu 2009;Dove et al 2011;Gibson et al 2016;Chen et al 2018;Zhao et al 2019Zhao et al , 2021Zhang et al 2022;Jiang et al 2022).…”

Section: Introductionmentioning

confidence: 99%

Solar coronal magnetic field measurements using spectral lines available in Hinode/EIS observations: Strong and weak field techniques and temperature diagnostics

Chen¹,

Bai²,

Tian³

et al. 2023

Preprint

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Recently, it has been proposed that the magnetic-field-induced transition (MIT) in Fe can be used to measure coronal magnetic field strengths. Several techniques, the direct line ratio technique and the weak and strong magnetic field techniques, are developed to apply the MIT theory to spectroscopic observations taken by EUV Imaging Spectrometer (EIS) onboard Hinode. However, the suitability of coronal magnetic field measurements based on the weak and strong magnetic field techniques has not been evaluated. Besides, temperature diagnostics is also important for measuring coronal magnetic field based on the MIT theory, but how to determine the accurate formation temperature of the Fe lines from EIS observations still needs investigation. In this study, we synthesized emissions of several spectral lines from a 3D radiation magnetohydrodynamic model of a solar active region, and then derived magnetic field strengths using different methods. We first compared the magnetic field strengths derived from the weak and strong magnetic field techniques to the values in the model. Our study suggests that both weak and strong magnetic field techniques underestimate the coronal magnetic field strength. Then we developed two methods to calculate the formation temperature of the Fe lines. One is based on differential emission measure analyses, and the other is deriving temperature from the Fe and Fe line pairs. However, neither of the two methods can provide temperature determination for accurate coronal magnetic field measurements as those derived from the Fe 174/175 and 184/345 Å line ratios. More efforts are still needed for accurate coronal magnetic field measurements using EIS observations.

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“…Most previous attempts only measured the stellar photospheric magnetic field based on the Zeeman effect of spectral lines (e.g., Johns-Krull & Valenti 2000;Donati et al 2008;Morin et al 2008;Reiners 2012;Kochukhov & Lavail 2017;Kochukhov & Shulyak 2019). Compared with the photospheric magnetic field, the coronal magnetic field is even more difficult to measure, which is the case for both the Sun and other stars (e.g., Yang et al 2020aYang et al , 2020bJiang et al 2022;Zhu et al 2022). There have been several attempts to make stellar coronal magnetic field measurements based on radio observations (e.g., Gary & Linsky 1981;Mutel et al 1985;Güdel 2002), which could be subject to uncertainties because the radio emission mechanisms are often not easy to determine.…”

Section: Introductionmentioning

confidence: 99%

Forward Modeling of Magnetic Field Measurements at the Bases of Stellar Coronae through Extreme-ultraviolet Spectroscopy

Liu

Chen

et al. 2022

ApJ

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Measurements of the stellar coronal magnetic field are of great importance for understanding stellar magnetic activity, yet such measurements have been extremely difficult to obtain. Recent studies proposed a new method of obtaining magnetic field measurements based on the magnetic-field-induced transition (MIT) of the Fe x ion. Here we construct a series of stellar coronal magnetohydrodynamics models and synthesize several Fe x emission lines at extreme-ultraviolet wavelengths, and then diagnose the magnetic field strength at the bases of the coronae using the MIT technique. Our results show that the technique can be applied to some stars with magnetic fields more than three times higher than that of the Sun at solar maximum. Furthermore, we investigate the uncertainty of the derived magnetic field strength caused by photon counting errors and find that a signal-noise ratio of ∼50 for the Fe x 175 Å line is required to achieve effective measurements of the stellar coronal magnetic field.

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Magnetohydrostatic modeling of the solar atmosphere

Cited by 12 publications

References 119 publications

Application of a Magnetic-field-induced Transition in Fe x to Solar and Stellar Coronal Magnetic Field Measurements

Application of a Magnetic-field-induced Transition in Fe x to Solar and Stellar Coronal Magnetic Field Measurements

Solar coronal magnetic field measurements using spectral lines available in Hinode/EIS observations: Strong and weak field techniques and temperature diagnostics

Forward Modeling of Magnetic Field Measurements at the Bases of Stellar Coronae through Extreme-ultraviolet Spectroscopy

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