Possible measurements of the magnetic field in eruptive prominences using the PROBA-3 coronagraph

The PROBA-3 mission will fly a spacecraft put in the shadow of a precisely occulting sister satellite orbiting “in formation” at a distance of 150 m in front of it to make artificial total eclipses. The region right above the solar limb will be studied for the first time over a coronal background not polluted by any spurious light. Although the priority will be the high-resolution fast imaging of the dynamic white-light corona, the use of a narrow filter centered on a low excitation D3 line of He I, is planned for imaging prominences. Adding the linear polarization analysis would permit the measurements of the magnetic field using the Hanle effect. We evaluate the possibility offered during the eruptive phase of a CME with prominence material inserted inside, for studying the associated magnetic field changes related to both the heating process and the ejection of material. The background highly polarized K-corona is taken into account. Sequences of quasi- simultaneous white-light processed images at high resolution are an additional feature of great interest for interpreting the overall magnetic structure.