相关论文: Spectropolarimetric diagnostics of unresolved magn…
The bulk of the quiet solar photosphere is thought to be significantly magnetized, due to the ubiquitous presence of a tangled magnetic field at subresolution scales with an average strength <B> ~ 100 G. This conclusion was reached through…
The Sun is the only star where we can resolve the intricate magnetism that all convective stars harbor. Yet, more than 99% of its visible surface along the solar cycle (the so-called quiet Sun) is filled with a tangled, unresolved…
Deciphering and understanding the small-scale magnetic activity of the quiet solar photosphere should help to solve many of the key problems of solar and stellar physics, such as the magnetic coupling to the outer atmosphere and the coronal…
The solar photosphere is filled by a magnetic field which is tangled on scales much smaller than the resolution capability of solar telescopes. This hidden magnetic field can be investigated via the Hanle effect. In 2007 we started a…
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…
The quiet Sun photospheric plasma has a variety of magnetic field strengths going from zero to 1800 G. The empirical characterization of these field strengths requires a probability density function (PDF), i.e., a function P(B) describing…
We present a series of radiative MHD simulations addressing the origin and distribution of mixed polarity magnetic field in the solar photosphere. To this end we consider numerical simulations that cover the uppermost 2-6 Mm of the solar…
The Hanle depolarization signals of Sr 4607 A have been used to estimate the unsigned magnetic flux and magnetic energy existing in the quiet Sun photosphere. However, the Sr 4607 A Hanle signals are not sensitive to the unsigned flux and…
One of the key research problems in stellar physics is to decipher the small-scale magnetic activity of the quiet solar atmosphere. Recent magneto-convection simulations that account for small-scale dynamo action have provided…
Analysis of the Hanle effect in solar molecular lines allows us to obtain empirical information on hidden, mixed-polarity magnetic fields at subresolution scales in the (granular) upflowing regions of the `quiet' solar photosphere. Here we…
Using turbulent MHD simulations (magnetic Reynolds numbers up to 8000) and Hinode observations, we study effects of turbulence on measuring the solar magnetic field outside active regions. Firstly, from synthetic Stokes V profiles for the…
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…
An attractive diagnostic tool for investigating the magnetism of the solar chromosphere is the observation and theoretical modeling of the Hanle and Zeeman effects in spicules, as shown in this letter for the first time. Here we report on…
Turbulent magnetic fields fill most of the volume of the solar atmosphere. However, their spatial and temporal variations are still unknown. Since 2007, during the current solar minimum, we are periodically monitoring several wavelength…
The magnetic topology of the solar photosphere in its quietest regions is hidden by the difficulties to disentangle magnetic flux through the resolution element from the field strength of unresolved structures. The observation of spectral…
Khomenko et al. estimate the mean magnetic field strength of the quiet Sun to be 20 G. The figure is smaller than several existing estimates, and it comes from the comparison between observed Zeeman polarization signals and synthetic…
This paper reviews some of the developments that over the last 10 years have allowed us to go from deciphering the physical origin of several of the enigmatic features of the second solar spectrum to discovering unknown aspects of the Sun's…
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…
The behavior of the observed polarization amplitudes with spatial resolution is a strong constraint on the nature and organization of solar magnetic fields below the resolution limit. We study the polarization of the very quiet Sun at…
We present spectro-polarimetric observations of Inter-Network magnetic fields at the solar disk center. A Fabry-Perot spectrometer was used to scan the two Fe I lines at 6301.5 A and 6302.5 A. High spatial resolution (0.5") magnetograms…