Quantitative Spectroscopy In 3D

The Advanced Spectrum Synthesis 3D Tool ASSET is introduced. ASSET allows for the accurate and fast calculation of spectra from 3D hydrodynamical models. To achieve the highest numerical accuracy 3(rd)-order Bezier interpolations are employed and all available information from the model grid with respect to the spacial and frequency resolution is exploited. ASSET is fully parallelized with OpenMP and MPI and highly optimized to run at about 25% of peak speed on workstations and clusters. The emergent flux for a single spectral line can be calculated from dozens of snapshots within a few minutes, and the whole spectrum (2 . 10(6) frequencies) can be calculated on a small cluster (a few hundred threads) within a day. The numerical methods, the serial optimization and the parallel implementation are described in some detail.