Filament or Prominence?
Both are the same. Filaments seen on the limb in emission are called prominences, while a prominence on the disc in absorption is called a filament. This movie shows a filament extending from the disc to the limb, where it can be seen as a prominence. A dark filament with a developing filament channel is visible at lower right. This clip has a great 3D effect. It was made from 1942-2116 UT on 20 Jan 2011
Many classification systems exist for prominences. Someone who tries to classify a prom by its shape often find difficulties as proms can change by the minute. I have seen sprays pierce quiescent proms, and seen half of a prom explode, while the other half remains attached to the disc. Some scholars have tried to classify them by spectral response, and others by magnetic strength. Too bad I don’t have advanced research grade spectrometers and magnetographs. For us little folks, most agree they can be divided into 2 groups, active and quiescent. Active proms are related to active areas, and often are associated with flares. Quiescent proms are found away from the active areas. Sometimes, a filament/prominence can have 1 end in an active region, while the other is in a quiet zone. Most armatures use the shape to classify a prom, with terms like “detached,” or “hedgerow.” Other common terms are sprays, loops, coronal cloud, surge, trees, flame, etc. one great read on the subject, and a must read for the amateur who just received a new H alpha scope, is this primer by David Knisely and is titled Observing the Sun in H alpha and can be found at this link http://www.prairieastronomyclub.org/halpha/
