Properties of solar eruptiions
There are basically three kinds of eruptions visible in Halpha:
1.Eruption by ejection, driven by surface events
a. collimated events, e.g. surges
b. irregular, flare-driven events
2.Eruption by instability.: filament eruptions
3. Little, highly frequent chromospheric events: spicules, mini-eruptions.
The eruption by ejection is the most spectacular. Surges are well-collimated
events which usually occur near large sunspots which organize their flow.
They apparently are ejected by a brightening at the base, but it is not
a substantial flare. They have been connected with type III bursts, so
energetic electrons are produced. Velocities to 200 Km/sec.
Flare-driven events are big and spectacular. In virtually all cases
the flare expels a filament overlying it. The filament rises slowly
in anticipation of flare onset. These are huge, energetic events, velocity
up to 2000 Km/sec.
All filaments eventually erupt or fade away; they never fall down. The
source is ome sort of instability, since they will erupt if an AR arises
beneath them. If the region is particularly quiet there may not be Halpha
emission or X- rays, but in an active region there will be two ribbon emission
and a gradual X-ray event. The much-discussed helical structure is rarely
seen, although eruption may show it.
We will show examples of each. I believe it is important to study these
phenomena before modelling them.
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