HAZEL (HAnle and ZEeman Light) 

Hanle and Zeeman Light is a computer program for the synthesis and inversion of Stokes profiles resulting from the joint action of atomic level polarization and the Hanle and Zeeman effects.


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 photosphere. To this end, it is important to develop rigorous diagnostic tools for the physical interpretation of spectropolarimetric observations in suitably chosen spectral lines. Here we present a computer program for the synthesis and inversion of Stokes profiles caused by the joint action of atomic level polarization and the Hanle and Zeeman effects in some spectral lines of diagnostic interest, such as those of the He I 1083.0 nm and 587.6 nm (or D3) multiplets. It is based on the quantum theory of spectral line polarization, which takes into account in a rigorous way all the relevant physical mechanisms and ingredients (optical pumping, atomic level polarization, level crossings and repulsions, Zeeman, Paschen-Back and Hanle effects). The influence of radiative transfer on the emergent spectral line radiation is taken into account through a suitable slab model. The user can either calculate the emergent intensity and polarization for any given magnetic field vector or infer the dynamical and magnetic properties from the observed Stokes profiles via an efficient inversion algorithm based on global optimization methods. This user-friendly diagnostic tool is offered to the astrophysical community, with the hope that it will facilitate new advances in solar and stellar physics.



 Here is a snapshot of the GUI for the synthesis.


Here are some snapshots of the inversion GUI.


The code is freely available to the community. However, we would like to have a list of the potential users and a form has to be filled in advance. Click here to proceed.


The main reference for the code that you should reference when publishing papers using Hazel is:

Other relevant publications for understanding the physics of polarization of the helium 10830 triplet and the quantum
theory of spectral line polarization on which Hazel is based on are:

  • Trujillo Bueno, J., & Asensio Ramos, A. 2007, "Influence of Atomic Polarization and Horizontal
    Illumination on the Stokes Profiles of the He I 10830 Å Multiplet", The Astrophysical Journal, 655, 642
    (ADS or free access pre-print)
  • Trujillo Bueno, J., Landi Degl'Innocenti, E., Collados, M., Merenda, L., & Manso Sainz, R. 2002,
    "Selective absorption processes as the origin of puzzling spectral line polarization from the Sun",
    Nature, 415, 403 (ADS or free access pre-print)
  • Trujillo Bueno, J., Merenda, L., Centeno, R., Collados, M., Landi Degl'Innocenti, E. 2005,
    "The Hanle and Zeeman Effects in Solar Spicules: A Novel Diagnostic Window on Chromospheric Magnetism",
    The Astrophysical Journal Letter, 619, L191 (ADS or free access pre-print)
  • Landi Degl'Innocenti, E., & Landolfi, M., "Polarization in Spectral Lines" (Kluwer) (Springer)

An introductory review paper with a gentle introduction to the Hanle and Zeeman effects is:
Trujillo Bueno, J. 2005,  "Quantum Spectropolarimetry and the Sun's Hidden Magnetism", in 11th European Solar Physics Meeting "The Dynamic Sun: Challenges for Theory and Observations" (ESA SP-600), ed. D. Danesy, S. Poedts, A. De Groof & J. Andries (PDF)