Issue |
A&A
Volume 442, Number 3, November II 2005
|
|
---|---|---|
Page(s) | L35 - L38 | |
Section | Letters | |
DOI | https://doi.org/10.1051/0004-6361:200500183 | |
Published online | 14 October 2005 |
Letter to the Editor
Forward modeling of coronal funnels
1
Kiepenheuer Institut für Sonnenphysik (KIS) Schöneckstraße 6, 79104 Freiburg, Germany e-mail: tayeb@kis.uni-freiburg.de
2
Institut d'Astrophysique Spatiale (IAS) CNRS-Université Paris XI, 91405 Orsay Cedex, France
3
FOM Institute for Plasma Physics Rijnhuizen Edisonbaan 14 3439 MN Nieuwegein, Netherlands
Received:
12
July
2005
Accepted:
11
September
2005
We propose a forward modeling approach of coronal funnels to investigate
the outer layers of the solar atmosphere with respect to their thermodynamical
properties and resulting emission line spectra.
We investigate the plasma flow out of funnels with a new
2D MHD time dependent model including the solar atmosphere all the way from the
chromosphere to the corona.
The plasma in the funnel is treated in the single-fluid MHD approximation
including radiative losses, anisotropic thermal conduction, and two different
parameterized heating functions.
We obtain plasma properties (e.g. density, temperature and
flow speed) within the funnel for each heating function.
From the results of the MHD calculation we derive spectral profiles of
a low corona emission line (, 770 Å).
This allows us e.g. to study the Doppler shifts
across the funnel.
These results indicate a systematic variation of the Doppler shifts in
lines formed in the low corona depending on the heating function used.
The line shift above the magnetic field concentration in the network is
stronger than in the inter-network in both cases.
However, for one of the heating functions, the maximum blue-shift (outflow)
is not to be found in the very center of the funnel but in the
vicinity of the center.
This is not the case of the second heating function where the maximum is
well aligned with the centre of the funnel.
This model directly relates for the first time the form of the heating
function to the thermodynamic and spectral properties of the plasma
in a funnel.
Key words: Sun / magnetohydrodynamics (MHD) / synthetic spectra / funnel
© ESO, 2005
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