Spicules
dominate
the chromospheres in
non-active re
gions
and h
ave been
studied exh austively.
They are
barely
visible, last only about
15 minutes, and resemble a "burning prarie". Some jets
can be seen shooting 10,000 km up fro m the Sun' s limb at velo cities of
about 30 km/sec. Studied exhaustivel y, they pre sent a num ber of
observing ch allenges, a s they are to o small to re solve and move so
quickly as to present wing-shift challenges.
Active Regions
are a
concentration o
f
magnetic acitivity with
several ty
pes of
features co ntained in
a close area.
Field Transition
Arches (FTA's)
connect P and F
spots – ele ments of
opposite polarity.
Inside a
n active
region, w
here
sunspots a
re
originally linked by
a
FTA, a shea r boundary forms.
Field Transition Arches are differen t
from
filaments in that they
are thin and not very dark. The
FTA usually has plage or granular structure underneath.
Plages
: Most of the
active re gion area i s
occupied by plage.
Considerable
atmospheric heating
takes p lace in th e
plage. It is bright in
everything from Halp ha to the Calci um H and K lines. Thi s he ating is
thought to account for an absen ce of spicule. While absent over plage,
spicule are prominent around its edges.
