相关论文: NLTE modeling of Stokes vector center-to-limb vari…
Weak entangled magnetic fields with mixed polarity occupy the main part of the quiet Sun. The Zeeman effect diagnostics fails to measure such fields because of cancellation in circular polarization. However, the Hanle effect diagnostics,…
The observed center-to-limb variation (CLV) of the scattering polarization in different lines of the Second Solar Spectrum can be used to constrain the height variation of various atmospheric parameters, in particular the magnetic fields…
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…
This paper addresses the modelling issue of the linearly-polarized solar limb spectrum, which is due to scattering processes and it offers a rich diagnostic potential for exploring solar magnetic fields via the Hanle effect. However, this…
The structure of the solar chromosphere is believed to be governed by magnetic fields, even in quiet-Sun regions that have a relatively weak photospheric field. During the past decade inversion methods have emerged as powerful tools for…
A big challenge in solar and stellar physics in the coming years will be to decipher the magnetism of the solar outer atmosphere (chromosphere and corona) along with its dynamic coupling with the magnetic fields of the underlying…
We present new observations of the center-to-limb variation of spectral lines in the quiet Sun. Our long-slit spectra are corrected for scattered light, which amounts to 4-8 % of the continuum intensity, by comparison with a Fourier…
The Zeeman effect is of limited utility for probing the magnetism of the quiet solar chromosphere. The Hanle effect in some spectral lines is sensitive to such magnetism, but the interpretation of the scattering polarization signals…
Observations of scattering polarization and the Hanle effect in various spectral lines are increasingly used to complement traditional solar magnetic field determination techniques. One of the strongest scattering polarization signals in…
Aims: The polarization of the Ca II resonant doublet (H and K lines) and the subordinate infrared triplet lines are key observables for diagnosing solar chromospheric magnetism. It is thus necessary to understand the physical mechanisms…
Due to the quick evolution of the solar chromosphere, its magnetic field cannot be inferred reliably without accounting for the temporal variations of its polarized light. This has been broadly overlooked in the modelling and interpretation…
Radiative transfer investigations of the solar Mg II h and k resonance lines around 280~nm showed that, while their circular polarization (Stokes V) signals arise from the Zeeman effect, the linear polarization profiles (Stokes Q and U) are…
We show a selection of high-sensitivity spectropolarimetric observations obtained over the last few years in the Ba II D2-line with the Zurich Imaging Polarimeter (ZIMPOL) attached to the Gregory Coude Telescope of IRSOL. The measurements…
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…
We highlight the main results of a three-dimensional (3D) multilevel radiative transfer investigation about the solar disk-center polarization of the Ca {\sc ii} 8542 \AA\ line. First, we investigate the linear polarization due to the…
The main goal of this thesis has been to investigate the effects that the macroscopic vertical velocity fields have on the scattering polarization signals formed in the solar chromosphere. Until now, the impact of macroscopic motions had…
Recent spectropolarimetric observations of active region filaments have revealed polarization profiles with signatures typical of the strong field Zeeman regime. The conspicuous absence in those observations of scattering polarization and…
We take a broad look at the problem of identifying the magnetic solar causes of space weather. With the lackluster performance of extrapolations based upon magnetic field measurements in the photosphere, we identify a region in the near UV…
We highlight the main results of a radiative transfer investigation on the magnetic sensitivity of the solar Mg ii k resonance line at 2795.5 angstrom, accounting for the joint action of the Hanle and Zeeman effects as well as partial…
Understanding the dynamics of the solar chromosphere is crucial to understanding energy transport across the solar atmosphere. The chromosphere is optically thick at many wavelengths and described by non-local thermodynamic equilibrium…