38 research outputs found
TIC: A Stokes inversion code for scattering polarization with partial frequency redistribution and arbitrary magnetic fields
We present the Tenerife Inversion Code (TIC), which has been developed to
infer the magnetic and plasma properties of the solar chromosphere and
transition region via full-Stokes inversion of polarized spectral lines. The
code is based on the HanleRT forward engine, which takes into account many of
the physical mechanisms that are critical for a proper modeling of the Stokes
profiles of spectral lines originating in the tenuous and highly dynamic
plasmas of the chromosphere and transition region: quantum level population
imbalance and interference (atomic polarization), frequency coherence effects
in polarized resonance scattering (partial frequency redistribution), and the
impact of arbitrary magnetic fields on the atomic polarization and the
radiation field. We present first results of atmospheric and magnetic
inversions, and discuss future developments for the project.Comment: 17pages, 7 figures. Accepted for publication in The Astrophysical
Journa
Atomic Scattering Polarization. Observations, Modeling, Predictions
This paper highlights very recent advances concerning the identification of new mechanisms that introduce polarization in spectral lines, which turn out to be key for understanding some of the most enigmatic scattering polarization signals of the solar visible spectrum. We also show a radiative transfer prediction on the scattering polarization pattern across the Mg ii h & k lines, whose radiation can only be observed from spac
Tomography of a solar plage with the Tenerife Inversion Code
We apply the Tenerife Inversion Code (TIC) to the plage spectropolarimetric
observations obtained by the Chromospheric LAyer SpectroPolarimeter (CLASP2).
These unprecedented data consist of full Stokes profiles in the spectral region
around the Mg II h and k lines for a single slit position, with around two
thirds of the 200 arcsec slit crossing a plage region and the rest crossing an
enhanced network. A former analysis of these data had allowed us to infer the
longitudinal component of the magnetic field by applying the weak field
approximation (WFA) to the circular polarization profiles, and to assign the
inferred magnetic fields to different layers of the solar atmosphere based on
the results of previous theoretical radiative transfer investigations. In this
work, we apply the recently developed TIC to the same data. We obtain the
stratified model atmosphere that fits the intensity and circular polarization
profiles at each position along the spectrograph slit and we compare our
results for the longitudinal component of the magnetic field with the
previously obtained WFA results, highlighting the generally good agreement in
spite of the fact that the WFA is known to produce an underestimation when
applied to the outer lobes of the Mg II h and k circular polarization profiles.
Finally, we use the inverted model atmospheres to give a rough estimation of
the energy that could be carried by Alfv\`en waves propagating along the
chromosphere in the plage and network regions, showing that it is sufficient to
compensate the estimated energy losses in the chromosphere of solar active
regions.Comment: Accepted for publication in The Astrophysical Journa
CLASP Constraints on the Magnetization and Geometrical Complexity of the Chromosphere-Corona Transition Region
The Chromospheric Lyman-Alpha Spectro-Polarimeter (CLASP) is a suborbital
rocket experiment that on 3rd September 2015 measured the linear polarization
produced by scattering processes in the hydrogen Ly- line of the solar
disk radiation, whose line-center photons stem from the chromosphere-corona
transition region (TR). These unprecedented spectropolarimetric observations
revealed an interesting surprise, namely that there is practically no
center-to-limb variation (CLV) in the line-center signals. Using an
analytical model, we first show that the geometrical complexity of the
corrugated surface that delineates the TR has a crucial impact on the CLV of
the and line-center signals. Secondly, we introduce a statistical
description of the solar atmosphere based on a three-dimensional (3D) model
derived from a state-of-the-art radiation magneto-hydrodynamic simulation. Each
realization of the statistical ensemble is a 3D model characterized by a given
degree of magnetization and corrugation of the TR, and for each such
realization we solve the full 3D radiative transfer problem taking into account
the impact of the CLASP instrument degradation on the calculated polarization
signals. Finally, we apply the statistical inference method presented in a
previous paper to show that the TR of the 3D model that produces the best
agreement with the CLASP observations has a relatively weak magnetic field and
a relatively high degree of corrugation. We emphasize that a suitable way to
validate or refute numerical models of the upper solar chromosphere is by
confronting calculations and observations of the scattering polarization in
ultraviolet lines sensitive to the Hanle effect.Comment: Accepted for publication in The Astrophysical Journal Letter