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scostep 2010 (stp12) - Leibniz-Institut für Atmosphärenphysik an der ...

scostep 2010 (stp12) - Leibniz-Institut für Atmosphärenphysik an der ...

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STP12 Abstracts<br />

Berlin, 12 - 16 July <strong>2010</strong><br />

SCOSTEP Symposium <strong>2010</strong><br />

Formation of shock waves in the solar corona <strong>an</strong>d near-Sun interpl<strong>an</strong>etary space<br />

M<strong>an</strong>n Gottfried<br />

Astrophysikalisches <strong>Institut</strong> Potsdam<br />

At the Sun, shock waves are produced either by flares <strong>an</strong>d/or by coronal mass ejections<br />

(CMEs). They are regarded to be the source of solar energetic particle events. In the solar<br />

corona, shock waves generate solar type II radio bursts. The propagation of a disturb<strong>an</strong>ce<br />

away from <strong>an</strong> active region through the corona into the interpl<strong>an</strong>etary space is consi<strong>der</strong>ed by<br />

evaluating the radial behaviour of the Alfven speed. The magnetic field of <strong>an</strong> active region is<br />

modelled by a magnetic dipole superimposed on that of the quiet Sun. Such a magnetic field<br />

structure leads to a local minimum of the Alfven speed in the r<strong>an</strong>ge 1.2-1.8 solar radii in the<br />

corona as well as a maximum of about 740 km/s at a dist<strong>an</strong>ce of 3.8 solar radii. The<br />

occurrence of such a local minimum <strong>an</strong>d maximum has import<strong>an</strong>t consequences on the<br />

formation <strong>an</strong>d development of shock waves in the corona <strong>an</strong>d the near-Sun interpl<strong>an</strong>etary<br />

space <strong>an</strong>d their ability to accelerate particles. That leads to a temporal delay of the onset of<br />

solar energetic particle events with respect to both the initial energy release (flare) <strong>an</strong>d the<br />

onset of the solar type~II radio burst.

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