Properties of Coronal Mass Ejections and related phenomena derived from visible-light and ultraviolet observations

Author: R. Susino

Affiliation: INAF – Osservatorio Astrofisico di Torino

Coronal Mass Ejections (CMEs) are one of the most impressive manifestations of the Sun’s activity and also one of the major drivers of Space Weather. During CMEs huge amounts of solar gas and magnetic field are released into the interplanetary space.
As CMEs expand in the solar corona, they can trigger shock waves that can in turn accelerate solar energetic particles (SEPs), while the ejected material may eventually travel towards the Earth and have the potential of causing severe consequences on human technologies and the terrestrial environment.
Over almost the last 20 years, CMEs have been extensively observed in visible light and ultraviolet by the SOHO and STEREO satellites. Coronagraphic, white-light images have been widely used with various techniques to derive speeds, masses, and geometrical properties of CMEs, as well as to validate theoretical models of initiation and propagation of such events. Nevertheless, possible explanations on how CMEs originate and evolve are still subject of open debate.
In this talk I will present results from several recent works demonstrating that combination of visible-light and ultraviolet data can provide unique information on the physical properties not only of the plasma embedded in the core of CMEs but also – under particular assumptions – of the ambient corona where CMEs propagate.