THREE-DIMENSIONAL RADIATIVE TRANSFER SIMULATIONS OF THE SCATTERING POLARIZATION OF THE HYDROGEN LY<i>α</i>LINE IN A MAGNETOHYDRODYNAMIC MODEL OF THE CHROMOSPHERE–CORONA TRANSITION REGION

Štěpán, Jiří; Bueno, J. Trujillo; Leenaarts, J.; Carlsson, Mats

doi:10.1088/0004-637x/803/2/65

Cited by 49 publications

(29 citation statements)

References 22 publications

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“…The Lyα line is, however, strongly influenced by 3D effects (Štěpán et al 2015;Sukhorukov & Leenaarts 2017), and this might have an influence on the results presented here. The green inner contour encloses 50% of all pixels and the outer contour 90%.…”

Section: Discussionmentioning

confidence: 77%

The Formation of IRIS Diagnostics. IX. The Formation of the C i 135.58 NM Line in the Solar Atmosphere

Lin

Carlsson

Leenaarts

2017

ApJ

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The C I135.58nm line is located in the wavelength range of NASA's Interface Region Imaging Spectrograph (IRIS) small explorer mission. We study the formation and diagnostic potential of this line by means of non localthermodynamic-equilibrium modeling, employing both 1D and 3D radiation-magnetohydrodynamic models. The C I/C II ionization balance is strongly influenced by photoionization by Lyα emission. The emission in the C I135.58nm line is dominated by a recombination cascade and the line forming region is optically thick. The Doppler shift of the line correlates strongly with the vertical velocity in its line forming region, which is typically located at 1.5 Mm height. With IRIS, the C I135.58nm line is usually observed together with the O I135.56nm line, and from the Doppler shift of both lines, we obtain the velocity difference between the line forming regions of the two lines. From the ratio of the C I/O I line core intensity, we can determine the distance between the C I and the O I forming layers. Combined with the velocity difference, the velocity gradient at mid-chromospheric heights can be derived. The C I/O I total intensity line ratio is correlated with the inverse of the electron density in the midchromosphere. We conclude that the C I135.58nm line is an excellent probe of the middle chromosphere by itself, and together with the O I135.56nm line the two lines provide even more information, which complements other powerful chromospheric diagnostics of IRIS such as the Mg II h and k lines and the C II lines around 133.5nm.

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Section: Discussionmentioning

confidence: 77%

The Formation of IRIS Diagnostics. IX. The Formation of the C i 135.58 NM Line in the Solar Atmosphere

Lin

Carlsson

Leenaarts

2017

ApJ

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“…The Lyα wings, which are insensitive to the Hanle effect, showed scattering polarization perpendicular to the solar limb with a clear center-to-limb variation (CLV) and amplitudes as large as 6% near the limb, in agreement with the theoretical predictions ). On the other hand, the line core, where the Hanle effect operates, showed Q/I and U/I signals of the order of 0.1%, but without a clear CLV in Q/I, in contrast with the theoretical line-core polarization signals calculated using stateof-the-art 1D and 3D models of the solar atmosphere (Trujillo Bueno et al 2011;Štěpán et al 2015). This discrepancy suggests that the geometrical complexity of the transition region, which is not realistic in such models, plays an important role on the Lyα scattering polarization (J.…”

Section: Introductionmentioning

confidence: 64%

Indication of the Hanle Effect by Comparing the Scattering Polarization Observed by CLASP in the Lyα and Si iii 120.65 nm Lines

Ishikawa

Bueno

Uitenbroek

et al. 2017

ApJ

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The Chromospheric Lyman-Alpha Spectro-Polarimeter is a sounding rocket experiment that has provided the first successful measurement of the linear polarization produced by scattering processes in the hydrogen Lyα line (121.57 nm) radiation of the solar disk. In this paper, we report that the Si III line at 120.65nm also shows scattering polarization and we compare the scattering polarization signals observed in the Lyα and Si III lines in order to search for observational signatures of the Hanle effect. We focus on four selected bright structures and investigate how the U/I spatial variations vary between the Lyα wing, the Lyα core, and the Si III line as a function of the total unsigned photospheric magnetic flux estimated from Solar Dynamics Observatory/Helioseismic and Magnetic Imager observations. In an internetwork region, the Lyα core shows an antisymmetric spatial variation across the selected bright structure, but it does not show it in other more magnetized regions. In the Si III line, the spatial variation of U/I deviates from the above-mentioned antisymmetric shape as the total unsigned photospheric magnetic flux increases. A plausible explanation of this difference is the operation of the Hanle effect. We argue that diagnostic techniques based on the scattering polarization observed simultaneously in two spectral lines with very different sensitivities to the Hanle effect, like Lyα and Si III, are of great potential interest for exploring the magnetism of the upper solar chromosphere and transition region.

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“…图 3 (网络版彩色)暗条形成的三维辐射MHD数值模拟 [72] Figure 3 (Color online) Filament formation obtained from a 3D RMHD simulation [72] 2. [74] .…”

Section: 除了本节简述的6个问题之外太阳辐射Mhd数mentioning

confidence: 99%

Research progress and future prospect of radiative magnetohydrodynamics numerical simulations in astrophysics and space physics

Yuan¹,

Chen²,

Li³

2018

Chin. Sci. Bull.

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THREE-DIMENSIONAL RADIATIVE TRANSFER SIMULATIONS OF THE SCATTERING POLARIZATION OF THE HYDROGEN LYαLINE IN A MAGNETOHYDRODYNAMIC MODEL OF THE CHROMOSPHERE–CORONA TRANSITION REGION

Cited by 49 publications

References 22 publications

The Formation of IRIS Diagnostics. IX. The Formation of the C i 135.58 NM Line in the Solar Atmosphere

The Formation of IRIS Diagnostics. IX. The Formation of the C i 135.58 NM Line in the Solar Atmosphere

Indication of the Hanle Effect by Comparing the Scattering Polarization Observed by CLASP in the Lyα and Si iii 120.65 nm Lines

Research progress and future prospect of radiative magnetohydrodynamics numerical simulations in astrophysics and space physics

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