Barczynski, Krzysztof ; Harra, Louise ; Janitzek, Nils ; Berghmans, David ; Verbeeck, Cis ; Zhukov, Andrei ; Zhu, Yingjie ; Varesano, Tania ; Mandrini, Cristina H. ; Valori, Gherardo

Talk presented at 10th Solar Orbiter Workshop, Berlin on 2026-03-19

Abstract: he origin of the slow solar wind remains an open question. Plasma upflows at active region borders are considered a possible source. The mechanisms driving these upflows are not fully understood, but proposed processes include: magnetic reconnection at different atmospheric layers, magnetoacoustic waves, small-scale heating events and others. We discuss such mechanisms in relation to observed atmospheric features to determine their relative importance. We analysed an upflow region observed on 29 March 2023 using data from Solar Orbiter, IRIS, and Hinode. Spectroscopic observations from Hinode/EIS and IRIS provided Doppler velocity maps spanning from the chromosphere to the corona, allowing the characterization of plasma dynamics in different layers. For the first time, we conducted a detailed temporal-series analysis of processes within upflow regions over a 4-hour period, using coordinated spectroscopic observations from IRIS (48 rasters), EIS (8 rasters), SPICE (500 rasters), and imaging data from EUI/HRI (3300 frames). A diagnostic method combining Doppler velocity map, magnetic field measurements and first ionization potential (FIP) bias was developed to infer the dominant drivers of the observed upflows. High-resolution images from EUI/HRI (Solar Orbiter), IRIS, and SDO/AIA were used to examine the connection between upflow mechanisms and coronal structures. Our results indicate that the strongest upflows originate in the upper transition region and lower corona, where magnetic reconnection between open and closed field lines likely plays a key role, but other mechanisms appear to act together to sustain the observed plasma upflows.

Keyword(s): EUI ; solar wind
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