相关论文: Atomic Polarization and the Hanle Effect
Scattering of light from an anisotropic source produces linear polarization in spectral lines and the continuum. In the outer layers of a stellar atmosphere the anisotropy of the radiation field is typically dominated by the radiation…
The Hanle effect in strong spectral lines is the physical mechanism that should be increasingly exploited for quantitative explorations of the magnetism of the quiet solar chromospheric plasma. Here we show, by means of multilevel radiative…
This paper reviews some of the most recent advances in the application of the Hanle effect to solar physics, and how these developments are allowing us to explore the magnetism of the photospheric regions that look ``empty'' in solar…
Although the spectral lines of hydrogen contain valuable information on the physical properties of a variety of astrophysical plasmas, including the upper solar chromosphere, relatively little is known about their scattering polarization…
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…
We present some theoretical predictions concerning the amplitude and magnetic sensitivity of the linear polarization signals produced by scattering processes in the hydrogen Ly-alpha line of the solar transition region. To this end, we have…
Diagnostic techniques for stellar magnetic fields based upon spectropolarimetry. We propose and explore a new technique based upon the linear polarization emitted in Hanle-sensitive lines in disk-integrated stars where a dipolar magnetic…
Optically pumped magnetometers usually rely on optical pumping using circularly- or linearly-polarized light. We study here zero-field magnetometers pumped with elliptically-polarized light, preparing both atomic orientation and alignment…
The polarization of radiation by scattering on an atom embedded in combined external quadrupole electric and uniform magnetic fields is studied theoretically. Limiting cases of scattering under Zeeman effect and Hanle effect in weak…
The polarization of radiation by scattering on an atom embedded in combined external quadrupole electric and uniform magnetic fields is studied theoretically. Analytic formulae are derived for the scattering phase matrix. Limiting cases of…
The quantum theory of polarized light allows one to model scattering in the solar atmosphere for inferring its properties. This powerful approach has revealed two key long-standing problems in solar physics: the puzzling dilemmas between…
We continue our studies of atomic alignment in diffuse media, in particularly, in interstellar and circumstellar media, with the goal of developing new diagnostics of magnetic fields in these environments. We understand atomic alignment as…
Recent spectropolarimetric observations of Herbig AeBe stellar systems show linear polarization variability with wavelength and epoch near their obscured H-alpha emission. Surprisingly, this polarization is not coincident with the H-alpha…
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 derive exact expressions for the degree of lineal polarization over a resolved or integrated stellar disc due to resonance scattering and the Hanle effect from a dipolar or quadrupolar distribution of magnetic fields. We apply the theory…
Magnetic fields play a key role in most astrophysical systems, from the Sun to active galactic nuclei. They can be studied through their effects on atomic energy levels, which produce polarized spectral lines. In particular, anisotropic…
A particularly interesting line for exploring the physical conditions of the quiet solar chromosphere is H$\alpha$, but its intensity profile is magnetically insensitive and the small circular polarization signatures produced by the…
The creation and detection of atomic polarization is examined theoretically, through the study of basic optical-pumping mechanisms and absorption and fluorescence measurements, and the dependence of these processes on the size of ground-…
This paper considers the problem of modeling the light polarization that emerges from an astrophysical plasma composed of atoms whose excitation state is significantly influenced by the anisotropy of the incident radiation field. In…
Hanle effect is ubiquitous in the study of spin-related phenomena and has been used to determine spin lifetime, precession and transport in semiconductors. Here, we report an experimental observation of anomalous Hanle effect in individual…