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Proposal ID Klein_140

Date of Proposal
97/12/11

firstname
Karl-Ludwig

lastname
Klein

institute
Paris Observatory

address
Observatoire de Meudon
DASOP
F-92195 MEUDON PRINCIPAL Cedex

email
klein@obspm.fr

phone
+ 33 1 45 07 77 61

fax
+33 1 45 07 79 59

proposal
Electron beams can be observed as they travel through the corona
by their decimetric and metric radio emission. It occurs in the
vicinity of the local electron plasma frequency (or its harmonic)
and is therefore a tracer of the ambient electron density.
When the beams travel from the low to the high corona, i.e. in
the direction of decreasing density, the emission shifts to lower
frequency in the course of the event. These are type III bursts
which are a frequent phenomenon in the corona. Less frequent are
bursts whose emission frequency shifts from low to high frequencies,
revealing beams travelling downward through the solar atmosphere.
These beams must have been accelerated high in the corona, and
their possible acceleration sites have not yet been well
identified. In a previous study of two events, we have shown
that the current sheet of a coronal streamer is a possible site,
at a height of about 1 solar radius above the photosphere
(Klein, Aurass, Soru-Escaut, Kalman 1997, Astron. Astrophys.
620, 612 - Erratum with the correctly printed figures in the
June III issue of A&A).

Using the Nancay Radioheliograph of Paris Observatory and the
Tremsdorf Radio spectrograph of the Potsdam Astrophysical Institute,
we have identified some recent bursts and need imaging observations
of the coronal plasma in order to identify the structures in
which the radio sources, whose positions are shown by the
radioheliographic data, are located. To this end we need EIT data
for the following days (whole day in order to see the relevant
structural changes of the configurations; all EIT wavelengths
in order to be able to make temperature maps):

1997 April 15
1997 September 12, 17, 19, 26
1997 October 1
1997 November 1.

This proposal involves K.-L. Klein and S. Theis (Meudon Observatory)
in collaboration with H. Aurass (Potsdam Astrophys. Institute).
Partners from the EIT team are J.P. Delaboudiniere and
C. Delannee (IAS Orsay).

Part of the proposed work involves a student research project
(S. Theis, Meudon). We would therefore appreciate a rapid answer.

inside_collab
EIT consortium member: J.P. Delaboudiniere (Orsay)

consortium
no

topic
Streamers

topic

title
Sites of electron acceleration in the midle & high corona


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