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ESPOS videos
European Solar Physics Online Seminars
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https://espos.stream
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Natural Sciences (Astrophysics and Astrononmy)
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shahin.jafarzadeh@astro.uio.no
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Large-amplitude oscillations in solar prominences derived from high-resolution simulations | Valeriia Liakh
Natural Sciences (Astrophysics and Astrononmy)
103 views
Date of upload:
19.05.2021
Co-author:
Caption:
We report 2D MHD simulations of the large-amplitude oscillations (LAOs) in the solar prominences performed with MHD code Mancha. We aim to study the properties of LAOs using high-resolution simulations in a simple 2D magnetic configuration that contains a dipped part. We loaded the dense prominence plasma in the dips region. In order to excite oscillations, we used a perturbation directed along the magnetic field. For the same numerical model, the four spatial resolutions were considered: 240, 120, 60, and 30 km. The longitudinal LAOs (LALOs) are strongly damped even in the high-resolution simulation in the region of the weaker and more curved magnetic field (at the center and bottom of the prominence). At the prominence top, the oscillations have relatively longer damping times. Furthermo
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Detection and dynamics of the vortex tubes in the solar atmosphere | Suzana de Souza e Almeida Silva
Natural Sciences (Astrophysics and Astrononmy)
110 views
Date of upload:
03.03.2021
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Caption:
We present the state-of-art detection method of three-dimensional vortices and apply it to realistic magneto-convections simulations performed by the MURaM code. The detected vortices extend from the photosphere to the low chromosphere, presenting similar behaviour at all height levels. The vortices concentrate the magnetic field, and thereby the plasma dynamics inside the vortex is considerably influenced by the Lorentz force. Rotational motions also perturb the magnetic field lines, but they lead to only slightly bent flux tubes as the magnetic field tension is too high for the vortex flow to significantly twist the magnetic lines. We find that twisted magnetic flux tubes are created by shear motions in regions where plasma-beta>1, regardless of the existence of flow vortices.
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The corrugated umbra model | Vasco Henriques
Natural Sciences (Astrophysics and Astrononmy)
132 views
Date of upload:
19.05.2021
Co-author:
Caption:
The chromosphere of the umbra of sunspots is a remarkably dynamic layer featuring extremely fine sub-arcsec structure. Such structures appear dark against enveloping umbral flashes, but also bright before or after a flash, other features still are bright throughout. Only recently did we start understanding such fine features and semi-empirical modelling is converging with simulations to provide insight, not only into such fine structure, but also into the umbral flash phenomenon itself. The observational evidence weighs overwhelmingly towards a strong corrugation of the umbra where the material in short dynamic fibrils over-extends in a column of upflowing material while the adjacent areas flash. The delayed small-scale umbral brightenings at the bottom of such columns are an out-of-phase
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The Dynamic and Magnetic Evolution of Arch Filament Systems | Sergio J. González Manrique
Natural Sciences (Astrophysics and Astrononmy)
103 views
Date of upload:
19.05.2021
Co-author:
Caption:
We study the dynamics of plasma along the legs of an arch filament system (AFS) observed with relatively high-cadence spectropolarimetric data from the ground-based solar GREGOR telescope (Tenerife) using the GREGOR Infrared Spectrograph in the He I 10830 Å range. The temporal evolution of the plasma of an AFS was followed using the chromospheric He I 10830 Å triplet and Si I 10827 Å. Measurements of vector magnetic fields in the solar chromosphere, especially in AFS, are extremely scarce, but very important. The magnetic field configuration reveals how AFSs are sustained in the chromosphere and hints at their formation, evolution, and disappearance. The magnetic field in the AFS follows loop-like structures traced by chromospheric absorption lines. However, if magnetic field lines follow

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