Issue |
A&A
Volume 417, Number 2, April II 2004
|
|
---|---|---|
Page(s) | 775 - 784 | |
Section | The Sun | |
DOI | https://doi.org/10.1051/0004-6361:20034452 | |
Published online | 19 March 2004 |
Evidence for the Hanle effect in molecular lines
1
Institute of Astronomy, ETH Zentrum, 8092 Zurich, Switzerland e-mail: fluri@astro.phys.ethz.ch
2
Astronomy Division, PO Box 3000, 90014 University of Oulu, Finland
Corresponding author: S. V. Berdyugina, sveta@astro.phys.ethz.ch
Received:
6
October
2003
Accepted:
15
December
2003
In many wavelength regions molecular lines dominate the second solar
spectrum that results from coherent scattering. Scattering
polarization is modified by magnetic fields via the Hanle effect. This
allows us to explore the magnetic field regime with weak field strengths
and mixed polarities, which is not seen with the Zeeman effect and thus
contains complementary information. Molecular lines are particularly
well suited to diagnose such turbulent fields because they exhibit a
broad range of magnetic sensitivities within narrow spectral
regions. Thus, it is possible to employ the technique of the
differential Hanle effect, i.e. to obtain field strengths by
observing polarization ratios in various lines. We have identified one
R- and one P-triplet of C2 at 5140 Å and 5141 Å, respectively,
that satisfy all conditions to be used in the differential Hanle
effect. Based on these lines we have developed a model that can
diagnose turbulent magnetic fields using the Hanle effect. The tool is
sensitive over a broad range of magnetic field strengths from a few
Gauss up to several hundred Gauss. This tool has allowed us to find a
significant Hanle depolarization of C2 lines in quiet Sun
observations, which corresponds to a magnetic field strength of
G.
Key words: line: formation / molecular processes / polarization / scattering / Sun: atmosphere / Sun: magnetic fields
© ESO, 2004
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