Göttingen 2025 – wissenschaftliches Programm
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EP: Fachverband Extraterrestrische Physik
EP 4: Sun and Heliosphere II
EP 4.2: Vortrag
Dienstag, 1. April 2025, 14:15–14:30, ZHG101
The inferred active region magnetic field at different vantage points: an analysis with SO/PHI and SDO/HMI — •Jonas Sinjan1, Johann Hirzberger1, Daniele Calchetti1, Sami K. Solanki1, Gherardo Valori1, Xiahong Li1, David Orozco Suárez2, Julián Blanco Rodríguez3, and Hanna Strecker2 — 1Max-Planck-Institut für Sonnensystemforschung, Göttingen, Deutschland — 2Instituto de Astrofísica de Andalucía, Granada, Spain — 3Universitat de València, Parterna-Valencia, Spain
The open flux problem is currently an unsolved mystery, representing a 2-3 factor mismatch between the open flux measured at 1 AU and that via remote sensing of the solar atmosphere and extrapolated to 1 AU. One explanation is that the open flux at the photosphere is underestimated, in particular in the polar regions. Until now it was impossible to test this with observations: Solar Orbiter (SO), with its on board magnetograph (the Polarimetric and Helioseismic Imager, PHI) has made this a reality such that the photospheric magnetic field can be observed simultaneously from two different vantage points.
First the impact of the viewing angle on the inferred magnetic field, open or closed, can be evaluated. From 12 - 17th October 2023 Solar Orbiter observed an active region (NOAA 13465) together with SDO/HMI, with an angular separation of 60-80 degrees. This dataset allows for the μ-correction (which assumes the field to be radial) to be observationally tested for the first time. A comparison will be shown of the evolution and magnitude of the magnetic field inferred by SO/PHI-HRT with that from SDO/HMI at these different vantage points.
Keywords: Solar Orbiter; Magnetic Field; Photosphere; HMI; PHI