Prominences

Abstract

The observations of the cool, dense sheets of plasma known as prominences have been summarised in Section 1.4.3 and in the books by Tandberg-Hanssen (1974) and Jensen et al (1979). Here the main aim is to dicuss the magnetic properties of quiescent prominences. The important aspects of radiative transfer and energy balance are outside the scope of this book, and there is not room to discuss the many types of active prominence. An exception is the loop prominence, which occurs after a prominence eruption (Section 10.3.2) and has been described in Section 10.3.3. The eruption of an active-region (or plage) prominence is generally violent: it may show up as a spray, and usually it gives rise to a two-ribbon flare. Quiescent prominences are much larger and have weaker fields; they erupt more gently and do not usually produce an Hα flare, but the basic instability may well be the same.