SOLARNET Conference: The Many Scales of the Magnetic Sun

Coronal Mass Ejections (CMEs) are in the center of interest for solar - terrestrial research. They are interesting both from the fundamental plasma physical and space weather perspectives. The integral part of CMEs are huge magnetic flux ropes where magnetic field lines wind about a common axis. They form when magnetic energy first accumulates in the solar corona and then lose its balance. After being released from the Sun, CMEs expand and propagate outwards into outer corona and interplanetary space. Their initial flux rope structure can change dramatically due to interactions with the ambient solar wind and with other eruptions. This presentation will review the key mechanism of how CMEs are believed to form and erupt from the Sun, and physical processes behind their early evolution. Understanding their nascent phase and evolution are paramount for reliable space weather forecasting. The status and challenges related to coronal modelling of CMEs are also discussed.