The View
through a Hydrogen Alpha Filter
When viewed
through a Hydrogen Alpha (Ha) filter, the sun comes alive!
Prominences - are clouds of partially-ionized gas in or slightly
above the Chromosphere which are confined by magnetic fields
(usually somewhat twisted or "sheared" fields). The fields confine
it helping form the prominence, almost like a natural "magnetic
bottle". The localized field of the prominence interacts with the
diverging global field of the rest of the sun causing the prominence
to be buoyant like a balloon.
The prominence is held down by
the anchor points of the local fields on the sun, usually on the
ends or in several places along the length of the prominence. Many
low prominences are held down almost continuously along their
length, while the larger quiescent prominences may only be held down
at a few anchor points (the Hedgerow prominence is a good example).
When the anchor points are
abruptly disturbed by emerging magnetic flux of the wrong polarity
or by surface field decay, the anchors are broken and the prominence
may actually "lift-off" from the surface because of its magnetic
buoyancy. We see this in what are known as "disparition brusque"
eruptions where the whole prominence rises up and takes off for deep
space (the most common mode of Coronal Mass Ejection by the way).
Sometimes the prominence/filament just vanishes,
while at other times, it rises and breaks up. This can also result
in what is known as a "spotless flare" where the surface detail
shows some brightening. You may also see these vanishing filaments
referred to as "filament eruptions".
Filaments - when a prominence is viewed from above it's
called a filament. Filaments snake across the sun like rivers of
cool plasma.
Spicules - are small jets of gas which are most often seen on
the limb in H-alpha or in the wings of H-alpha near the edges of the
elements of the Chromospheric network. Spicules have been compared
to blowing, burning grass in a prairie.
Spicules are concentrated on the
boundaries of super-granulation cells, and can have lifetimes of 5 to 10
minutes, and are about 1000 km across and 10,000 km long.
Why Ha? |
The View |
What you see |
The Chromos |
Ha Emission |
Bandwidth |
Main Designs |
Ha Components |
Rear Filters |
The Etalon |
Front Filters |
Coronado filters
| DayStar Filters
| Solar Spectrum Filters
