I would hold up my hand against the sun squeezing my fingers
tightly together and see the outlines of their bones, nature’s X-Ray machine. But
the sun could do so much more. It could sprinkle sparkles across the lake,
dancing on the waves like fairy elves beckoning to join them in a cooling
splash or even send many different coloured rays on the edges of my mother’s
large hallway mirror.
I’d check and count the different colours of light with my
right eye and then recheck with my left and count again the lights splitting
into rainbow colours. My grandfather would at times worry then warn me, to
stand in front of a mirror is vain, but I did not notice my own reflection, I
saw the wonders of the sun.
As children we didn’t see the sun as an efficient machine
with many intricate parts we saw it as a happy sun drawn somewhere on the left
hand corner of a page or a sad sun if it would rain.
The sun is so much more complex we all strive to understand
and still, each time I look up to see the sun there is something new to behold,
something new that makes me want to understand. And so today I still chase the
wonders of the sun.
Trudi
Coronal holes are of very low density (typically 100 times
lower than the rest of the corona) and have an open magnetic field structure;
in other words, magnetic field lines emerging from the holes extend
indefinitely into space rather than looping back into the photosphere. This
open structure allows charged particles to escape from the Sun and results in
coronal holes being the primary source of the solar wind and the exclusive
source of its high-speed component.
During the minimum years of the solar cycle, coronal holes
are largely confined to the Sun's polar regions (although some exceptions have
been observed by SOHO), while at solar maximum they can open up at any
latitudes.
Solar Magnetic Tornadoes
We report the discovery of abundant 'magnetic tornadoes' above the surface of the Sun. Magnetic tornadoes resemble tornadoes on the Earth but have a magnetic skeleton and are hundreds to thousands times larger in diameter. One such observed tornado occupies the area equivalent of Europe or the USA.
We find that magnetic tornadoes have swirling speeds of many 10,000 km/hour. Magnetic tornadoes transport energy from the Sun's surface into its uppermost layer, the corona, where they contribute to the heating of the Sun's outer atmosphere. Consequently, magnetic tornadoes may well be the crucial missing piece of a long-standing puzzle in astrophysics: the heating of the outer solar and stellar atmospheres.
We estimate that there are as many as 11,000 of these swirling events above the Sun's surface at all times. The discovery has been made possible through state-of-the-art technology, namely the combination of extremely high resolution observations from the Swedish 1-m Solar Telescope located at La Palma [Canary Isl.] with data from the NASA's space-borne Solar Dynamics Observatory. With the help of state-of-the-art 3-D numerical simulations of the solar atmosphere, we unraveled the fascinating physics of this new and important phenomena.
This discovery will be published in the journal Nature on June 28th, 2012. It will also be featured on the cover page.
Importance of magnetic tornadoes: One would expect that the atmosphere of the Sun should become cooler with increasing distance from its surface. Remarkably, the opposite occurs and the temperature rises to over a million degrees. How the atmosphere is heated to these temperatures is a fundamental question of modern astrophysics, also referred to as coronal heating problem. Solving the heating problem is crucial for understanding our Sun, including the generation of the solar `wind' and its impact on the Earth's atmosphere (e.g. solar storms, Northern lights) and spacecraft in Earth's Orbit (e.g. satellite communication disruption). It is generally believed that large magnetic arcades that exist in the Sun's outer regions, which are anchored to the bubbling Sun surface, can transport outwards the energy required for heating. We have discovered an alternative but widespread way of transporting enough energy for atmospheric heating due to relentless twisting of the magnetic arcades at their footpoints. A manifestation of this twisting appears close to the Sun surface, which we observe in incredible detail, and describe as a `solar magnetic tornado'.
Credit:
Solar Magnetic Tornadoes - Text, Image & Animation
With permission from
Dr. Sven Wedemeyer-Böhm University of Oslo, Norway
http://folk.uio.no/svenwe/
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