Speaker
Description
Metis on board of Solar Orbiter is the space coronagraph developed by an Italian-German-Czech consortium. It is capable of observing solar corona and various coronal structures in the visible-light (VL) and UV (hydrogen Lyman $\alpha$) channels simultaneously for the first time. Here we present observations of a large eruptive prominence of April 25-26, 2021,
in the VL, taken during the mission cruise phase, and demonstrate that apart from the broad-band continuum emission which is due to the Thomson scattering on prominence electrons we detect a significant radiation in the neutral-helium D$_3$ line (587.6 nm) which lies within the Metis VL passband. We show how the prominence looks like in the Stokes $I$, $Q$, and $U$. We consider two extreme cases of the prominence magnetic field, and we separate the Stokes $I$ and $Q$ signals pertinent to Thomson scattering and to the D$_3$ line.
The degree of linear polarisation of the D$_3$ line (both $Q$ and $U$) indicates the presence of the prominence magnetic field, hence Metis can serve as a magnetograph for eruptive prominences located high in the corona.
