Lagg et al. (2004)
The HeLIx code is based on fitting the observed Stokes profiles with synthetic ones obtained from an analytic solution of the Unno-Rachkovsky equations in a Milne-Eddington atmosphere.
These synthetic profiles are functions of the magnetic field strength |B|, its inclination and azimuth, the line-of-sight velocity, the Doppler width, the damping constant, the ratio of the line center to the continuum opacity, and the slope of the source function and the source function at tau=0. The atmospheric parameters that ensure the minimum of the merit function are obtained using a very reliable genetic algorithm (PIKAIA). This algorithm reaches the global minimum of the merit function with higher reliability than a classical Levenberg-Marquardt algorithm, which is also implemented in the code.
The code is able to handle an arbitrary number of atmospheric components. Atomic data files allow the flexible usage for various spectral lines. The code is able to directly read several data formats, such as Hinode and TIP-2 FITS files.
Download HeLIx. Download pdf-information about the code.
For questions, please contact Andreas Lagg (lagg[at]mps.mpg.de)