Issue |
Astron. Astrophys. Suppl. Ser.
Volume 144, Number 1, May II 2000
|
|
---|---|---|
Page(s) | 169 - 180 | |
DOI | https://doi.org/10.1051/aas:2000202 | |
Published online | 15 May 2000 |
Microwave tomography of solar magnetic fields
1
Special Astrophysical Observatory, S. Petersburg, Russia
2
Pulkovo Astronomical Observatory, S. Petersburg, Russia
3
Metsähovi Radio Observatory, Kylmälä, Finland
4
Nobeyama Radio Observatory, Japan
Send offprint request to: S. Urpo
Received:
28
October
1998
Accepted:
25
February
2000
We present a new technique for the measurement of magnetic fields
in the solar chromosphere - corona through observations of its
free-free microwave emission in intensity and polarization. We
derive the decoupled radiation transfer equations for Stoke's
parameters of I and V for circular polarized emission in
plane-layer inhomogeneous atmospheres and present a model
solutions of inversion problem. We discuss the discrimination
between contributions from the corona and the chromosphere to the
observed brightness spectra from the quiet Sun and plage regions
and propose a practical method of magnetic field estimates, which
was used both with single frequency (the Nobeyama Radioheliograph
at 17 GHz) and multi frequency (RATAN at GHz) observations
and discuss the preliminary results. The proposed techniques may
be useful as microwave
magnetography at the corona base and
for checks and improvements in the current problem of
extrapolating magnetic fields from photosphere to corona.
Key words: polarization / radiative transfer / methods: data analysis Sun: magnetic fields / Sun: radio radiation
© European Southern Observatory (ESO), 2000