Speaker
Description
First Name: Jiri
Last Name: Stepan
Affiliation: Astronomical Institute, Czech Academy of Sciences
All Authors: J. Stepan, P. Heinzel, S. Jejcic, R. Susino, and the Metis Team.
Abstract: METIS on Solar Orbiter measures polarized visible light in the VL channel (580–640 nm), recording linear polarization only. The He I D3 line at 587.6 nm lies within this passband; under suitable thermodynamic conditions (e.g., cool, dense prominence material embedded in the hot corona), resonance scattering in D3 can contribute significantly to the total VL signal. Because the line’s scattering polarization is modified by magnetic fields via the Hanle effect, reducing the polarization fraction and rotating its angle, the detected D3 contribution offers sensitivity to coronal magnetic fields. This opens a path to quantitative constraints on the field in eruptive prominences and coronal mass ejections observed by METIS. We outline an analysis framework that jointly treats the D3 line and the K-coronal continuum and discuss key challenges: limited observables (no Stokes V), line-continuum mixing, and background subtraction. Due to these limitations, we aim for a posterior distribution, not a single best-fit vector, of field strength and geometry, using Bayesian inference to derive credible intervals for the magnetic configuration.