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| <color red > ** New :** </color> | <color red > ** New :** </color> [[science:results:SeminLPP | October : Seminar on THEMIS at the Plasma Physics Laboratory, Paris (FR).]] \\ |
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| [[science:resources | Downloadable posters highlighting recent high-resolution observations of solar active regions by THEMIS]]\\ | [[science:resources | Downloadable posters highlighting recent high-resolution observations of solar active regions by THEMIS]]\\ |
| [[science:results:ESTFrance2025 | June : Presentation of THEMIS results at the EST France 2025 Workshop in Paris (FR).]] \\ | |
| [[science:results:SF2A2025 | July : Presentation of THEMIS results at the "Journées de la SF2A" in Toulouse (FR).]] \\ | |
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| Click for information on: \ \ **[[admin:location| How to reach THEMIS locations]]** \ ; \ **[[admin:contacts| How to contact the THEMIS team]]** | Click for information on: \ \ **[[admin:location| How to reach THEMIS locations]]** \ ; \ **[[admin:contacts| How to contact the THEMIS team]]** |
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| == THEMIS image of the month: June 2025 == | == THEMIS image of the month: September 2025 == |
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| <html> <a href="https://www.themis.iac.es/lib/exe/fetch.php?media=science:gallery:protu:solarfilament_meteospace_2025june05.jpg"> <img src="https://www.themis.iac.es/lib/exe/fetch.php?media=science:gallery:protu:solarfilament_meteospace_2025june05.jpg" alt="Solar filament observations on June 5th 2025." style="width: 100%; height: auto;"></a></html> \\ | <columns 100% l 60> |
| | <html> <a href="https://www.themis.iac.es/lib/exe/fetch.php?media=science:gallery:schema:opticalpath_tao.png |
| | "> <img src="https://www.themis.iac.es/lib/exe/fetch.php?media=science:gallery:schema:opticalpath_tao.png |
| | " alt="Diagram of THEMIS adaptive optic light-path." style="width: 100%; height: auto;"></a></html> \\ |
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| In June, during an observation campaign lead by researchers from the Paris Observatory (France) and the University of Wroclaw (Poland), THEMIS observed solar filaments. Solar filaments are large magnetised structure of the solar corona confining cold chromospheric-like plasma. Thanks to its specific magnetic structure, solar filaments plasma, of a temperature of about 10 000°K, "hangs" thermally isolated from the million °K solar corona. As this dense and cool plasma absorbs the light emitted from the lower solar layer, the filament appears dark relatively to the background.\\ | <newcolumn 40%> |
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| The THEMIS observation presented here results from two reconstructed images obtained from two adjacent scans over the solar filament with the THEMIS spectrograph slit. The two scans, which have a 80" range with a 0.5" spatial step, are then stitched together to obtain a larger field of view of about 110" x 90". Only the reconstructed image in the core of Hα line is displayed here, but THEMIS data allow to sample the full range of the Hα line with a spectral resolution of 4mÅ.\\ | THEMIS design, laid out in the 1980's, predate the revolution of adaptive optics (AO), and hence didn't foresee its installation. AO has since proved to be an indispensable technology of all modern high-resolution telescope. The core of the THEMIS overhaul that took place in the second half of the 2010's had the installation of a simple AO at the core of its objective. |
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| THEMIS high-resolution observations are very complementary to the observations of the [[https://www.oca.eu/fr/lag-physol-projects?option=com_content&view=category&layout=blog&id=295&Itemid=908 | Meteospace/3SOLEIL]] solar surveillance service of OCA/CNRS-INSU, which provide full-Sun high cadence (every 10s) Hα observations, presented on the right panel. \\ | |
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| Thanks to its high-resolution, as illustrated in the left panel, THEMIS permits to analyse the filamentary structure of the solar filament and understand its magnetic field thanks to THEMIS polarised measurements. In particular, the magnetic properties of the "barbs" of the filament, the features which extend away from the "spine" (the filament axis), remains ill understood and an active topic of research. | The installation of the [[technical:tao|THEMIS AO]] was thus particularly challenging as it required to deal with the limited existing available space. The entry prism is thus located just inside the spectrograph container, close to its roof, in a location that is not easily accessible. In addition, as shown in the diagram of TAO, it imposed to place the wavefront sensor optical bench (as well as the scanning mirror) outside of the THEMIS spectrograph container, in a vertical layout. |
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