LOTUS (non-LTE Optimization Tool Utilized for the derivation of atmospheric Stellar parameters) is a python package for the derivation of stellar parameters, such \(T_{\mathrm{eff}}\), \(\mathrm{log\mathit g}\), \(\mathrm{[Fe/H]}\) and \(\xi_{t}\) via Equivalent Width (EW) method with the assumption of 1D Non Local Thermodynamic Equilibrium. It mainly applies on the spectroscopic data from high resolution spectral survey. It can provide extremely accurate measurement of stellar parameters compared with non-spectroscipic analysis from benchmark stars as: \(\Delta T_{\mathrm{eff}} \lesssim 50 K\), \(\Delta \mathrm{log\mathit g} \lesssim 0.1\). LOTUS provides features:

  • Fast optimizer for obtaining stellar parameters based on Differential Evolution algorithm.

  • Well constrained uncertainty of derived stellar parameters from slice-sampling MCMC from PyMC3.

  • Interpolation of Curve of Growth from theoretical EW grid under the assumptions of LTE and Non-LTE.

  • Visualization of excitation and ionization balance when at the optimal combination of stellar parameters.

LOTUS is being developed in GitHub Repository, so if you catch any issues during running it please open an issue here.