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- De Pontieu, B., et al.
(författare)
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Rapid Temporal Variability of Faculae: High-Resolution Observations and Modeling
- 2006
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Ingår i: The Astrophysical Journal. - : American Astronomical Society. - 0004-637X .- 1538-4357. ; 646:2, s. 1405-1420
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Tidskriftsartikel (refereegranskat)abstract
- We present high-resolution G-band observations (obtained with the Swedish 1 m Solar Telescope) of the rapid temporal variability of faculae, which occurs on granular timescales. By combining these observations with magnetoconvection simulations of a plage region, we show that much of this variability is not intrinsic to the magnetic field concentrations that are associated with faculae, but rather a phenomenon associated with the normal evolution and splitting of granules. We also show examples of facular variability caused by changes in the magnetic field, with movies of dynamic behavior of the striations that dominate much of the facular appearance at 0.1" resolution. Examples of these dynamics include merging, splitting, rapid motion, apparent fluting, and possibly swaying.
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- van der Voort, Luc H. M. Rouppe, et al.
(författare)
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Ultra-high-resolution observations of plasmoid-mediated magnetic reconnection in the deep solar atmosphere
- 2023
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 673
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Tidskriftsartikel (refereegranskat)abstract
- Context. Magnetic reconnection in the deep solar atmosphere can give rise to enhanced emission in the Balmer hydrogen lines, a phenomenon referred to as Ellerman bombs.Aims. To effectively trace magnetic reconnection below the canopy of chromospheric fibrils, we analyzed unique spectroscopic observations of Ellerman bombs in the Hα line.Methods. We analyzed a 10 min data set of a young emerging active region observed with the prototype of the Microlensed Hyperspectral Imager (MiHI) at the Swedish 1-m Solar Telescope (SST). The MiHI instrument is an integral field spectrograph that is capable of achieving simultaneous ultra-high resolution in the spatial, temporal, and spectral domains. With the combination of the SST adaptive optics system and image restoration techniques, MiHI can deliver diffraction-limited observations if the atmospheric seeing conditions allow. The data set samples the Hα line over 4.5 Å with 10 mÅ pix−1, with 0.″065 pix−1 over a field of view of 8.″6 × 7.″7, and at a temporal cadence of 1.33 s. This constitutes a hyperspectral data cube that measures 132 × 118 spatial pixels, 456 spectral pixels, and 455 time steps.Results. There were multiple sites with Ellerman bomb activity associated with strong magnetic flux emergence. The Ellerman bomb activity is very dynamic, showing rapid variability and a small-scale substructure. We found a number of plasmoid-like blobs with full-width-half-maximum sizes between 0.″1 and 0.″4 and moving with apparent velocities between 14 and 77 km s−1. Some of these blobs have Ellerman bomb spectral profiles with a single peak at a Doppler offset between 47 and 57 km s−1.Conclusions. Our observations support the idea that fast magnetic reconnection in Ellerman bombs is mediated by the formation of plasmoids. These MiHI observations demonstrate that a microlens-based integral field spectrograph is capable of probing fundamental physical processes in the solar atmosphere.
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| 5. |
- van Noort, Michiel, et al.
(författare)
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Stokes imaging polarimetry using image restoration at the Swedish 1-m solar telescope
- 2008
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 489:1, s. 429-440
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Tidskriftsartikel (refereegranskat)abstract
- Aims. We aim to achieve both high spatial resolution and high polarimetric sensitivity, using an earth-based 1m-class solar telescope, for the study of magnetic fine structure on the surface of the Sun. Methods: We use a setup with 3 high-speed, low-noise cameras to construct datasets with interleaved polarimetric states, particularly suitable for Multi-Object Multi-Frame Blind Deconvolution image restorations. We discuss the polarimetric calibration routine and various potential sources of error in the results. Results: We obtained near diffraction limited images, which have a noise level of ≈ 10-3 I_cont. We confirm that dark cores have a weaker magnetic field and a lower inclination angle with respect to the solar surface than the edges of the penumbral filament. We demonstrate that the magnetic field strength in faculae-striations is significantly lower than in other nearby parts of the faculae.
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| 8. |
- Henriques, Vasco, et al.
(författare)
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Photospheric Temperatures from Ca II H
- 2010
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Ingår i: Magnetic Coupling between the Interior and Atmosphere of the Sun. - Berlin, Heidelberg : Springer.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The temperature stratification in the upper photosphere can be extracted from Ca II H&K spectrograms following Shine and Linsky (1974) by assuming LTE, the Eddington-Barbier approximation, hydrostatic equilibrium, and that Ca II is mostly in the ground state. Rouppe van der Voort (2002) confirmed that these assumptions were solid for a wide range in the Ca IIK wings and further developed the method including forward computation using MULTI (Carlsson 1986).
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| 10. |
- Jurčák, Jan, et al.
(författare)
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Recent advancements in the EST project
- 2019
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Ingår i: Advances in Space Research. - : Elsevier BV. - 0273-1177 .- 1879-1948. ; 63:4, s. 1389-1395
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Tidskriftsartikel (refereegranskat)abstract
- The European Solar Telescope (EST) is a project of a new-generation solar telescope. It has a large aperture of 4 m, which is necessary for achieving high spatial and temporal resolution. The high polarimetric sensitivity of the EST will allow to measure the magnetic field in the solar atmosphere with unprecedented precision. Here, we summarise the recent advancements in the realisation of the EST project regarding the hardware development and the refinement of the science requirements.
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