 Charged particles follow magnetic field lines that rise vertically from
a sunspot – an area of strong magnetic field. On the edges of the
sunspot, the magnetic field lines bend over to connect to regions of
the opposite polarity (Image: Hinode JAXA/NASA)
source NewScientist
The restless bubbling and frothing of the Sun's chaotic surface is
astonishing astronomers who have been treated to detailed new images
from a Japanese space telescope called Hinode.
The observatory will have as dramatic an impact on our understanding
of the Sun as the Hubble Space Telescope has had on our view of the
universe beyond, scientists told a NASA press conference in Washington,
DC, US, on Wednesday.
 Long filaments of plasma connect regions of different magnetic polarity
in the chromosphere, a thin layer of the Sun's atmosphere lying between
its visible surface, or photosphere, and its outer corona (Image:
Hinode JAXA/NASA)
"Everything we thought
we knew about X-ray images of the Sun is now out of date," says Leon
Golub from the Harvard-Smithsonian Center for Astrophysics in
Cambridge, Massachusetts, US. "We've seen many new and unexpected
things. For that reason alone, the mission is already a success."
Hinode (Japanese for "sunrise") was launched
in September 2006 to study the solar magnetic field and how magnetic
energy is released as the field rises into the Sun's outer atmosphere.
The mission was formerly known as Solar-B.
Seething and swaying
The
spacecraft carries an optical solar telescope (SOT), an X-ray telescope
(XRT) and an ultraviolet spectrometer. It orbits the Earth in a
permanent twilight zone between night and day, which gives it a
continuous view of the Sun.
Hinode has sent
back startling images of the Sun's outer limb. Where astronomers
expected to see a calm region called the chromosphere, they saw a
seething mass of swaying spikes (see image below right, and watch a video of the spikes taken by Hinode).
"These
structures are 8000 kilometres long and some extend twice that high,"
says SOT science team member Alan Title from Lockheed Martin Advance
Technology Center in Palo Alto, California, US. "Their speed is such
that if you sat on the end of one, which I don't recommend, you could
travel from Washington, DC, to San Francisco in about four minutes.
These things are really moving."
Crashing loops
Another
surprise sighting is that of giant magnetic field loops crashing down
onto the Sun's surface as if they were collapsing from exhaustion, a
finding that Golub describes as "impossible". Previously, scientists
thought they should emerge from the Sun and continue blowing out into
space.
"Almost every day, we look at the data and we say – what the heck was that?" says Golub, a member of the XRT science team.
Astronomers
do not yet know what to make of the surprises, but they hope Hinode
will help solve many big puzzles. One is that the temperature of the
Sun's tenuous outermost atmosphere, or corona, is far hotter than the
layers underneath, which are nearer its energy-generating core.
Scientists
believe that tangled magnetic fields must somehow dump energy in the
corona. "Theorists suggested that twisted, tangled magnetic fields
might exist," says Golub. "With the XRT, we can see them clearly for
the first time."
Astronomers hope Hinode's
clear view of the Sun will also help them identify the magnetic field
configurations that lead to the most explosive energy releases of all.
That would enable better forecasts of stormy "space weather", when
solar eruptions can interfere with satellite communications and disrupt
electricity supply networks on the ground.
 Long filaments of plasma connect regions of different magnetic polarity
in the chromosphere, a thin layer of the Sun's atmosphere lying between
its visible surface, or photosphere, and its outer corona (Image:
Hinode JAXA/NASA)
**
by Hazel Muir
21.03.2007
source NewScientist
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