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Metis, the coronagraph on board Solar Orbiter, provides for the first timecoronagraphic imaging in the ultraviolet HI Ly-alpha line and, simultaneously,in polarized visible light, thus providing a host of information on theproperties of CMEs and solar eruptions like their overall dynamics, timeevolution, mass content, and outflow propagation velocity in the expandingcorona. We analyzed in this work six CMEs observed by Metis between April andOctober 2021, which are characterized by a very strong HI Ly-alpha emission. Westudied in particular the morphology, kinematics, and the temporal and radialevolution of the emission of such events, focusing on the brightest UVfeatures. The kinematics of the eruptive events under consideration werestudied by determining the height-time profiles of the brightest parts on theMetis plane of the sky. Furthermore, the 3D position in the heliosphere of theCMEs were determined by employing co-temporal images from two othercoronagraphs: LASCO/C2 onboard SOHO, and COR2 onboard STEREO-A. Finally, theradiometrically calibrated Metis images of the bright UV features were analyzedto provide estimates of their volume and density. From the kinematics andradiometric analyses, we obtained indications of the temperatures of the brightUV cores of these events. The analysis of these strong UV-emitting featuresassociated with coronal mass ejections demonstrates the capabilities of thecurrent constellation of space coronagraphs, Metis, LASCO/C2, and COR2, inproviding a complete characterization of the structure and dynamics of eruptiveevents in their propagation phase from their inception up to several solarradii. Furthermore, we show how the unique capabilities of the Metis instrumentto observe these events in both HI Ly-alpha line and polarized VL radiationallow plasma diagnostics on the thermal state of these events.

Eruptive events with exceptionally bright emission in HI Ly-alpha observed by the Metis coronagraph