Bibcode
Trujilo-Bueno, J.; Manso Sainz, R.
Bibliographical reference
Il Nuovo Cimento C, vol. 025, Issue 5-6, p.783
Advertised on:
9
2002
Citations
7
Refereed citations
5
Description
The only way to obtain reliable empirical information on the intensity
and topology of the weak magnetic fields of the quiet solar chromosphere
is via the measurement and rigorous physical interpretation of
polarization signals in chromospheric spectral lines. The observed
Stokes profiles reported here are due to the Hanle and Zeeman effects
operating in a weakly magnetized plasma that is in a state far from
local thermodynamic equilibrium. The physical origin of their enigmatic
linear polarization Q and U components is the existence of atomic
polarization in their metastable lower-levels, which permits the action
of a dichroism mechanism that has nothing to do with the transverse
Zeeman effect. It is also pointed out that the population imbalances and
coherences among the Zeeman sublevels of such long-lived atomic levels
can survive in the presence of horizontal magnetic fields having
intensities in the gauss range, and produce significant polarization
signals. Finally, it is shown how the most recent developments in the
observation and theoretical modelling of weak polarization signals are
facilitating fundamental new advances in our ability to investigate the
magnetism of the outer solar atmosphere via spectropolarimetry.