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 …
Context. According to our current understanding, a subclass of the upper main-sequence chemically peculiar stars, called mercury- manganese (HgMn), is non-magnetic. Nevertheless, chemical inhomogeneities were recently discovered on their surfaces. At …
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 …
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 …
Context. The weak, turbulent magnetic fields that supposedly permeate most of the solar photosphere are difficult to observe, because the Zeeman effect is virtually blind to them. The Hanle effect, acting on the scattering polarization in suitable …
Polarimetry is a powerful tool for detecting and characterizing exoplanets and protoplanetary disks as light scattered from circumstellar material is linearly polarized. We present the first light results of ExPo (Extreme Polarimeter) [1], a …
In polarimetry, it is important to characterize the polarization properties of the instrument itself to disentangle real astrophysical signals from instrumental effects. This article deals with the accurate measurement and modeling of the …
The photospheric magnetic field outside of active regions and the network has a ubiquitous and dynamic line-of-sight component that strengthens from disk center to limb as expected for a nearly horizontal orientation. This component shows a striking …