Complex sentence: A typical coronal mass ejection may have any or all of three distinctive features: a cavity of low electron density, a dense core (the prominence, which appears as a bright region on coronagraph images embedded in this cavity), and a bright leading edge.
Split into simpler sentences: A typical coronal mass ejection may have any or all of three distinctive features. These are, a cavity of low electron density, a dense core (the prominence), which appears as a bright region on coronagraph images embedded in this cavity, and a bright leading edge.