Göttingen 2025 – wissenschaftliches Programm
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EP: Fachverband Extraterrestrische Physik
EP 10: Poster Session
EP 10.21: Poster
Donnerstag, 3. April 2025, 11:00–12:30, ZHG Foyer 1. OG
Investigating high-speed outflows from a coronal hole with UV spectroscopy — •Mario Roco-Moraleda1, Luca Teriaca1, Pradeep Chitta1, Ziwen Huang1, Hardi Peter1,2, and Sami Solanki1 — 1Max-Planck-Institut für Sonnensystemforschung, Justus-von-Liebig-Weg 3, 37077 Göttingen, Germany — 2Institut für Sonnenphysik (KIS), Georges-Köhler-Allee 401a, 79110 Freiburg, Germany
Coronal holes have been known since decades to be the main source regions of the solar wind. Recent very high resolution observations from the HRIEUV telescope of the EUI instrument on Solar Orbiter show evidence that the fast solar wind and the Alfvénic slow wind originate from largely unipolar, open field region characterized by low emission in coronal lines (T = 1 MK). Those observations draw a connection between speeds on the plane of sky of about 100-150 km/s at a few tens of megameter above the solar surface and picoflare jets, with kinetic energy content in the range of 10^21 to 10^24 erg, at the base of the corona in these dark areas.
However, classical spectroscopic observations (line of sight velocities) in lines formed at the base of the corona (T=0.6 MK) do not show evidence of upflow velocities above about 10 km/s, difficult to reconcile with the HRIEUV observations.
We revisit high quality SUMER observations of an on-disk equatorial coronal hole. We perform a very accurate wavelength calibration and analysis of the spectral profiles to detect signature of high-speed flows occurring at spatial scales below 1" resolution of the instrument.
Keywords: Coronal holes; Solar corona; Spectroscopy; EUV; Solar wind