POLARIZATION

Data-reduction techniques for high-contrast imaging polarimetry. Applications to ExPo

Context. Imaging polarimetry is a powerful tool for detecting and characterizing exoplanets and circumstellar environments. Polarimetry allows a separation of the light coming from an unpolarized source such as a star and the polarized source such as …

First Detection of Linear Polarization in the Line Profiles of Active Cool Stars

The application of high-resolution spectropolarimetry has led to major progress in understanding the magnetism and activity of late- type stars. During the last decade, magnetic fields have been discovered and mapped for many types of active cool …

The search for magnetic fields in mercury-manganese stars

Context. A subclass of the upper main-sequence chemically peculiar stars, mercury-manganese (HgMn) stars were traditionally considered to be non-magnetic, showing no evidence of variability in their spectral line profiles. However, discoveries of …

Spatial mapping of the Hanle and Zeeman effects on the Sun

Spatial mapping of the Hanle and Zeeman effects on the Sun has been done for the first time, through Stokes vector imaging with a narrow- band (0.2 ̊A) universal filter. It is shown how the polarization signatures of the Hanle and Zeeman effects can …

Influence of magnetic fields on the coherence effects in the Na I D$_1$ and D$_2$ lines

To clarify the physical nature of the enigmatic scattering polarization in the Na i D$_1$ and D$_2$ line cores we have explored their behavior with full Stokes vector polarimetry in regions with varying degree of magnetic activity near the solar …

Anomalous polarization effects due to coherent scattering on the Sun

The richly structured linearly polarized spectrum that is produced by coherent scattering in the Sun's atmosphere contains a number of spectral features for which no explanation has been found within the standard scattering theory. According to this …

Center-to-limb variation of the enigmatic NaI D_1 and D_2 polarization profiles

The remarkable polarization structure of the Na I D_1 and D_2 lines that is due to coherent scattering has remained an enigma, since it has not yet been possible to find an explanation that is consistent with both current understanding of quantum …

Differential Hanle effect and the spatial variation of turbulent magnetic fields on the Sun

While diagnostic techniques based on the ordinary Zeeman effect (e.g. magnetograms) are almost ``blind'' to a turbulent magnetic field with mixed magnetic polarities within the spatial resolution element, the Hanle effect is sensitive to this domain …

Center-to-limb variation of the second solar spectrum.

The linear polarization that is caused by scattering processes in the solar atmosphere has been refered to as the ``second solar spectrum'', since it is structurally as rich as the ordinary intensity spectrum but quite different in appearance and …

The second solar spectrum. A new window for diagnostics of the Sun.

The Sun's radiation becomes linearly polarized by coherent scattering processes in the solar atmosphere. With a novel polarimetry system that achieves a precision of 1e-5 in the degree of polarization, the previously largely unexplored territory of …