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Proposal ID GABRYL_60

Date of Proposal
96/12/20

firstname
Jean-Rene

lastname
GABRYL

institute
Royal Observatory of Belgium

address
Observatoire Royal de Belgique
Avenue Circulaire 3
B-1180 Bruxelles
BELGIUM

email
Jean-Rene.Gabryl@oma.be

phone
32 2 373 02 37

fax
32 2 373 02 24

proposal
As the Sun has reached its minimum of activity, large coronal holes
dominate in polar regions where the main part of the emitted radiation
is due to polar plumes. The relative contribution of the background
corona is still known with poor accuracy. However, in order to determine
the physical conditions and the particles velocities in the polar holes,
an accurate knowledge of the background corona is necessary. We propose
a method to deduce this background corona from EIT observations.

As an image results from the integration along the lines of sight,
the polar signal is masked by lower latitude contributions. In order
to extract the proper polar radiation, we assume that the EUV corona
is optically thin and that the polar holes are stable and slowly
changing with time. By averaging images through one solar rotation,
the polar emission is enhanced with respect to the lower latitude
contribution which is just spatially smoothed. We then modelize this
average with a radial emissivity profile deduced from equatorial regions
which we use to remove all non-polar signal in polar holes.

inside_collab
F.Clette, J.-F. Hochedez

consortium
yes

topic
Polar Holes

topic

title
EUV BACKGROUND EMISSION IN POLAR HOLES FROM EIT IMAGES


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