Magneto-static Modeling from Sunrise/IMaX: Application to an Active Region Observed with Sunrise II

Wiegelmann, T.; Neukirch, T.; Nickeler, D. H.; Solanki, S. K.; Barthol, P.; Gandorfer, A.; Gizon, Laurent; Hirzberger, J.; Riethmüller, T. L.; Noort, M. van; Rodríguez, J. Blanco; Iniesta, J. C. del Toro; Suárez, D. Orozco; Schmidt, Wolfgang; Pillet, V. Martı́nez; Knölker, M.

doi:10.3847/1538-4365/aa582f

Cited by 27 publications

(33 citation statements)

References 49 publications

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“…In test II, the MHS extrapolation takes about 6.5 CPU hours on a 2.1GHz processor. An application to IMaX vector magnetogram embedded by HMI data (about 2000 × 2000 grids, see Wiegelmann et al (2017)) needs large amount of computational resources. For practical application, we can limit calculation to the Sunrise-FOV (936 × 936) to reduce the computation.…”

Section: Influence Of Noisementioning

confidence: 99%

On the Extrapolation of Magnetohydrostatic Equilibria on the Sun

Zhu

Wiegelmann

2018

ApJ

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Modeling the interface region between solar photosphere and corona is challenging, because the relative importance of magnetic and plasma forces change by several orders of magnitude. While the solar corona can be modeled by the force-free assumption, we need to take care about plasma forces (pressure gradient and gravity) in photosphere and chromosphere, here within the magneto-hydro-static (MHS) model. We solve the MHS equations with the help of an optimization principle and use vector magnetogram as boundary condition. Positive pressure and density are ensured by replacing them with two new basic variables. The Lorentz force during optimization is used to update the plasma pressure on the bottom boundary, which makes the new extrapolation works even without pressure measurement on the photosphere. Our code is tested by using a linear MHS model as reference. From the detailed analyses, we find that the newly developed MHS extrapolation recovers the reference model at high accuracy. The MHS extrapolation is, however, numerically more expensive than the nonlinear force-free

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Section: Influence Of Noisementioning

confidence: 99%

On the Extrapolation of Magnetohydrostatic Equilibria on the Sun

Zhu

Wiegelmann

2018

ApJ

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“…Rather, they play a role in heating their local surroundings, if they release their energy at these layers. Jafarzadeh et al (2017a) showed with the help of the magnetostatic solution of Wiegelmann et al (2017) that the shorter SCFs map fields that are more vertical. A number of the transverse waves we have identified are found along these short fibrils.…”

Section: The Structures Listed Inmentioning

confidence: 99%

Transverse Oscillations in Slender Ca ii H Fibrils Observed with Sunrise/SuFI

Jafarzadeh

Solanki

Gafeira

et al. 2017

ApJS

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We present observations of transverse oscillations in slender Ca IIH fibrils (SCFs) in the lower solar chromosphere. We use a 1 hr long time series of high-(spatial and temporal-) resolutionseeing-free observations in a 1.1 Å wide passband covering the line core of Ca IIH 3969 Å from the second flight of the SUNRISE balloon-borne solar observatory. The entire field of view, spanning the polarity inversion line of an active region close to the solar disk center, is covered with bright, thin, and very dynamic fine structures. Our analysis reveals the prevalence of transverse waves in SCFs with median amplitudes and periods on the order of 2.4±0.8 km s −1 and 83±29 s, respectively (with standard deviations given as uncertainties). We find that the transverse waves often propagate along (parts of) the SCFs with median phase speeds of 9±14 km s −1. While the propagation is only in one direction along the axis in some of the SCFs, propagating waves in both directions, as well as standing waves are also observed. The transverse oscillations are likely Alfvénic and are thought to be representative of magnetohydrodynamic kink waves. The wave propagation suggests that the rapidhigh-frequency transverse waves,often produced in the lower photosphere, can penetrate into the chromospherewith an estimated energy flux of ≈15 kW m −2. Characteristics of these waves differ from those reported for other fibrillar structures, which, however, were observed mainly in the upper solar chromosphere.

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“…These extrapolations are based on magnetohydrostatic equilibria and have been described by Wiegelmann et al (2017). They also employ wider FOV but lower resolution and lower sensitivity SDO/HMI data (Pesnell et al 2012;Schou et al 2012).…”

Section: Observations From Sunrise 31 Observations and Reductionmentioning

confidence: 99%

“…Deviations from force-free fields occur mainly below 2 Mm in the mixed plasma-β upper photosphere and chromosphere. For more detail, see Wiegelmann et al (2017). We limit our displays to the FOV of the SUNRISE/IMaX images and to a height of up to only 1400 km for better visualization.…”

Section: Magnetic Field Extrapolation Using a Magnetostaticmentioning

confidence: 99%

Slender Ca ii H Fibrils Mapping Magnetic Fields in the Low Solar Chromosphere

Jafarzadeh¹,

Rutten²,

Solanki³

et al. 2017

ApJS

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A dense forest of slender bright fibrils near a small solar active region is seen in high-quality narrowband Ca II H images from the SuFI instrument onboard the SUNRISE balloon-borne solar observatory. The orientation of these slender Ca II H fibrils (SCF) overlaps with the magnetic field configuration in the low solar chromosphere derived by magnetostatic extrapolation of the photospheric field observed with SUNRISE/IMaX and SDO/HMI. In addition, many observed SCFs are qualitatively aligned with small-scale loops computed from a novel inversion approach based on best-fit numerical MHD simulation. Such loops are organized in canopy-like arches over quiet areas that differ in height depending on the field strength near their roots.

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Magneto-static Modeling from Sunrise/IMaX: Application to an Active Region Observed with Sunrise II

Cited by 27 publications

References 49 publications

On the Extrapolation of Magnetohydrostatic Equilibria on the Sun

On the Extrapolation of Magnetohydrostatic Equilibria on the Sun

Transverse Oscillations in Slender Ca ii H Fibrils Observed with Sunrise/SuFI

Slender Ca ii H Fibrils Mapping Magnetic Fields in the Low Solar Chromosphere

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