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In a recent Letter to The Astrophysical Journal (Fischer et al., 2020) we report on cases of granular lanes showing magnetic activity.

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Das größte europäische Sonnenteleskop GREGOR, das von einem deutschen Konsortium betrieben wird und sich am Teide Observatorium in Spanien befindet, hat gestochen scharfe Bilder der Feinstruktur der Sonne aufgenommen. Nach einer umfassenden Neugestaltung der GREGOR-Optik durch ein Team von Wissenschaftlern und Ingenieuren des Leibniz-Instituts für Sonnenphysik (KIS) kann die Sonne von Europa aus mit einer höheren Auflösung als je zuvor beobachtet werden.

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The first images from ESA/NASA's new Sun-observing spacecraft Solar Orbiter were released to the public on 16 July 2020. It carries 10 scientific instruments, including the Photospheric-Helioseismic Imager (PHI) for which KIS has built an Image Stabilization System (ISS).

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Numerical simulations provide great insight into the various wave phenomena that occur in the solar atmosphere. However, a proper comparison with the observations of the real Sun require us to understand how these phenomena affect spectral lines. Synthetic observables derived from numerical simulation are becoming necessary as they help us to properly interpret observational data.

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The stability of sunspots is one of the long-standing unsolved puzzles in the field of solar magnetism and the solar cycle. The thermal and magnetic structure of the sunspot beneath the solar surface is not accessible through observations, thus processes in these regions that contribute to the decay of sunspots can only be studied through theoretical and numerical studies.

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For the past year, all departments of KIS worked together to carry out the biggest change of GREGOR since its inauguration. By replacing the relay optics and rearranging the AO and the majority of the instruments in the optics lab, we were able to significantly improve GREGOR's image quality and prepare the telescope for future instrumentation upgrades.

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Magnetic flux cancelation refers to the interaction of opposite polarity magnetic elements leading to magnetic flux removal from the solar surface. If the interacting elements are previously unconnected, their cancelation is treated as an observational signature of magnetic reconnection.

Using high-resolution data obtained with the GREGOR telescope on Tenerife, we witnessed such a magnetic field reconnection event. The Integral Field Unit (IFU, built by Instituto de Astrofísica de Canarias, IAC) of the GREGOR Infrared Spectrograph (GRIS) recorded the Stokes profiles in the photospheric Si i 10827Å spectral line targeting the quiet-Sun at disk center.

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On Monday, February 10, 2020 at 5:03 a.m. (CET), the ESA satellite Solar Orbiter was successfully launched with an Atlas 5 rocket from the Cape Canaveral Air Force Station in Florida. In less than 2 years the satellite will reach an orbit around the sun, where it can start scientific observations.

 

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Am 11. November 2019 beobachteten und registrierten KIS-Wissenschaftler zusammen mit C. Schmidt von der Boston University den Merkurtransit vor der Sonne mit den Teleskopen GREGOR und Chrotel. Merkurtransite sind seltene Ereignisse; der nächste Transit wird erst 2032 stattfinden. Solche Transite sind eine großartige Gelegenheit, die Exosphäre des Merkurs zu erforschen. Das erste Bild dieser Exosphäre wurde von H. Schleicher vom KIS während des vorletzten Transits im Jahre 2003 mit dem VTT-Teleskop in der Spektrallinie von Natrium aufgezeichnet.

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Inversion codes for the radiative transfer equation are tools that allow us to determine the temperature, magnetic field and plasma velocity in the solar atmosphere from spectro-polarimetric observations (i.e. Stokes vector) in spectral lines as a function of the optical depth.

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