An international team of astronomers, including
Silja Pohjolainen of Tuorla
Observatory, have observed a type of explosion on the
surface of the Sun called a coronal mass ejection (CME),
which releases super-heated gases into space. The fact
that the CME comes from a very small, rather than a quite
large region on the Sun, has come as a surprise to
astronomers.
The team, put together by Tuorla Observatory researcher
Silja
Pohjolainen and Lidia van Driel-Gesztelyi at Paris
Observatory, included researchers from Argentina, Finland,
France, Hungary and the United Kingdom. Silja Pohjolainen
discovered the so called 'X-ray bright point' when working
with archival data from the Metsähovi
Radio Telescope, which has been used to monitor the
Sun for many years.
Understanding the source of outbursts from the Sun such
as this has not only academic but also very practical
implications. The plasma clouds which are ejected consist
of high energy particles which cause beautiful auroras,
but can also lead to radio transmission disturbances,
power blackouts, satellite damage and harm astronauts --
an area of research which has become known as space
weather. Space weather researchers now know that they have
to keep track of the behaviour of even the small regions
on the Solar surface and not just the large ones!
The research has appeared in the journal
Astronomy
and Astrophysics, 434, 725.
More on the solar research group at Tuorla here.
Posted 30th May 2005.
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An image of the Sun made with the Yohkoh satellite,
which operates at X-ray wavelengths. The small central dot (marked
by a square), is a region about the same size as the Earth. An
outburst of plasma, called a coronal mass ejection (CME), has been
detected from this region, an observation which came as quite a
surprise to astronomers, as CMEs have always previously been linked
to huge complexes of sunspots. How frequent such outbursts from
small solar regions is still unclear, and is likely to be an
important topic for future space missions.
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