Determining elemental composition in laboratory meteorite ablation spectra through radiative transfer modeling
Laboratory simulations of meteor ablation provide a critical quantitative link between the chemical composition of meteoroids and their observed spectral features. In this work, we analyzed high-resolution Echelle spectra (wavelength range 380-780 nm) of 22 diverse meteorites from the dataset presented in our previous work (Matlovič et al., 2024), representing the largest collection of laboratory meteor analogs to date. Using a radiative transfer model assuming local thermodynamic equilibrium (LTE) and accounting for self-absorption in optically thick plasma, we derived plasma parameters and elemental abundances for both major (Fe, Mg, Cr, Mn, Si, Na, Ni, Li, and K) and minor (Co, Cu, and V) species. Comparison with known bulk meteorite compositions allowed us to validate the modeling approach and assess chemical biases resulting from laboratory-induced ablation. Our analysis suggested plasma temperatures between 5220 and 5810 K and revealed systematic discrepancies in the elemental abundances compared to the original chemical composition. Specifically, we observed a significant enhancement of volatile species (Na, K) relative to Fe, accompanied by a depletion of the moderately volatile element Mg, while refractory elements (Al, Ca, Ti) remained undetected in the plasma radiation. These trends are consistent with the equilibrium vaporization model and demonstrate that under the simulated entry conditions ($\sim$12 km/s at $\sim$80 km altitude), the ablation process is dominated by incomplete and fractional vaporization. We conclude that while laboratory spectra of plasma from ablated meteorites do not fully reflect the original bulk composition, radiative transfer modeling effectively characterizes the state of the radiating plasma, offering a more robust approach for interpreting compositional properties from meteor observations.