We present time-resolved spectroscopy and circular spectropolarimetry of the SW Sex star RXJ1643.7+3402. We find significant polarization levels exhibiting a...
The Motion of Magnetic Flux Tubes in the Convection Zone and the Subsurface Origin of Active Regions
The rise of kink-unstable magnetic flux tubes through the solar convection zone is discussed with a view to explaining the subsurface origin of active regions...
The multi-component field topology of sunspot penumbrae. A diagnostic tool for spectropolarimetric measurements
Context: .Sunspot penumbrae harbor highly structured magnetic fields and flows. The moving flux tube model offers an explanation for several observed phenomena...
The Physical Origin of the Scattering Polarization of the Na I D Lines in the Presence of Weak Magnetic Fields
We demonstrate that the atomic alignment of the hyperfine-structure components of the ground-level S1/2 of Na I and of the upper-level P1/2 of the D1 line are...
The Physics of Twisted Magnetic Tubes Rising in a Stratified Medium: Two-dimensional Results
The physics of a twisted magnetic flux tube rising in a stratified medium is studied using a numerical MHD code. The problem considered is fully compressible...
The Polarimetric and Helioseismic Imager on Solar Orbiter
Aims: This paper describes the Polarimetric and Helioseismic Imager on the Solar Orbiter mission (SO/PHI), the first magnetograph and helioseismology instrument...
The polarization angle in the wings of Ca I 4227: A new observable for diagnosing unresolved photospheric magnetic fields
Context. When observed in quiet regions close to the solar limb, many strong resonance lines show conspicuous linear polarization signals, produced by...
The Polarization Signature of Photospheric Magnetic Fields in 3D MHD Simulations and Observations at Disk Center
Before using three-dimensional (3D) magnetohydrodynamical (MHD) simulations of the solar photosphere in the determination of elemental abundances, one has to...