Issue |
A&A
Volume 382, Number 3, FebruaryII 2002
|
|
---|---|---|
Page(s) | L17 - L21 | |
Section | Letters | |
DOI | https://doi.org/10.1051/0004-6361:20011777 | |
Published online | 15 February 2002 |
Letter to the Editor
Scattering polarization of molecular emission lines in the quiet solar chromosphere
1
Département Cassini, UMR 6529, Observatoire de la côte d'Azur, BP 4229, 06304 Nice, France
2
UMR 5572, Observatoire Midi-Pyrénées, 14 avenue Édouard Belin, 31400 Toulouse, France
Corresponding author: M. Faurobert, faurob@obs-nice.fr
Received:
8
November
2001
Accepted:
13
December
2001
We present scattering polarization measurements performed with THEMIS
in July 2000 near the south polar limb. The low level of scattered light at THEMIS, which is
the only large solar telescope to include a superpolished primary mirror, allows,
in good seeing conditions, to observe the emission spectrum of
the low chromosphere above the limb. These are, as far as we know, the
first high spectral resolution observations of the intensity and the
first measurements of the polarization
of and
molecular lines in emission above the limb.
Molecules are present in a thin layer in the region of the temperature
minimum between the photosphere and the chromosphere. We present a very simple
model for the formation of the polarized lines and we relate the
observed polarization rates
to the so-called intrinsic line polarizability coefficients W2. Those
quantities may be derived from quantum mechanical computations involving
the solution of the Schrödinger equation for the molecular potential.
Solar observations provide a direct way of checking these heavy computations
and contribute to the improvement of our knowledge in molecular physics.
Nine
molecular transitions and two
transitions are present in our
spectral window; we find that for the
transitions,
the polarizability is between 0.13 and 0.26 and that it takes
higher values, namely 0.41 and 0.46, for the two
transitions.
Key words: techniques: polarimetric / techniques: spectroscopic / Sun: atmosphere / Sun: polarization / spectral lines: scattering
© ESO, 2002
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