Presentation 1 : None
THEMIS Observations of the Second Solar Spectrum (PNST)
J. Arnaud and M. Faurobert
The term "second solar spectrum" has been coined for the rich scattering polarization spectrum observed near the solar limb.
It provides new diagnostic opportunities for weak magnetic
fields using the Hanle effect. Weak magnetic fields seem to be
present everywhere in the solar atmosphere while strong magnetic
fields cover only a tiny percentage of the solar surface.
The polarization amplitudes for most lines of this spectrum are
or the order of 10^{-3} or smaller. THEMIS proves to be an excellent telescope for observing weak polarizations.
We present THEMIS observations of scattering polarization, near
the limb and also in the chromosphere just above the limb and
some interpretation in terms of turbulent magnetic field. We also
deduce from our data the intrinsic line polarizability coefficients
W_{2} for C_{2} and MgH molecular lines.