The linear polarization produced by scattering processes in the spectral lines of the IR triplet of Ca II can be observed near the edge of the solar disk. The cause of this polarization was considered a true enigma until the year 2003, in which IAC researchers could carry out sophisticated calculations based on the quantum theory of the spectral line polarization. In this way, they could demonstrate that the physical origin of the enigmatic polarization is the presence of "atomic polarization" in the lower levels of such spectral lines, which produces dichroism (i.e., selective absorption of the polarization components of the radiation beam that propagates towards the observer) without the need of a magnetic field. This result is important because it provides a way to detect extremely weak magnetic fields in Astrophysics, both in the solar atmosphere and in other astrophysical plasmas (e.g., in the atmospheres of supernovae).
It may interest you
When the Sun is observed in X-ray or extreme ultraviolet wavelengths, hundreds of bright and compact structures with a rounded shape and sizes similar to that of our planet Earth can be easily distinguished in the solar corona. These structures are known as Coronal Bright Points or CBPs and they consist of sets of magnetic loops that connect areas of opposite magnetic polarity on the solar surface. These loops confine the solar plasma and in them, by mechanisms that have been debated for many years among solar physicists, the gas remains with temperatures of several million degrees, emittingAdvertised on
In this work we discuss and confront recent results on metallicity variations in the local interstellar medium, obtained from observations of H II regions by our group and neutral clouds (from literature) of the Galactic thin disk, and compare them with recent high-quality metallicity determinations of other tracers of the chemical composition of the interstellar medium as B-type stars, classical Cepheids, and young clusters. We find that the metallicity variations obtained for these last kinds of objects are consistent with each other and with that obtained for H II regions butAdvertised on
We present the results of our spatially resolved investigation into the interplay between the ages of the stellar populations and the kinematics of the warm ionised outflows in the well-studied type II quasar Markarian 34. Utilising integral field spectroscopic (IFS) data, we determine the spatial distribution of the young stellar population (YSP; age < 100 Myr) using spectral synthesis modelling. We also employ the 5007 [OIII] emission line as a tracer of the warm ionised gas kinematics. We demonstrate a spatial correlation between the outer edges of the advancing side of the outflow and anAdvertised on