Metal-poor stars NLTE abundances of Eu

In this work, we used NLTE line formation, as well as one-dimensional (1D) hydrostatic and spatial averages of three-dimensional hydrodynamical (<3D>) model atmospheres to measure the abundance of Eu based on both the EuII 4129{AA} and EuII 6645{AA} lines for solar spectra and metal-poor stars. We find that for EuII 4129{AA} line the NLTE modeling leads to higher (0.04dex) solar Eu abundance in 1D and higher (0.07dex) in <3D> NLTE while NLTE modeling leads to higher (0.01dex) solar Eu abundance in 1D and lower (0.03dex) in <3D> NLTE for EuII 6645{AA} line.

Although the NLTE corrections for the EuII {lambda} 4129{AA} and EuII {lambda} 6645{AA} lines are opposite, the discrepancy between the abundances derived from these individual lines reduces after applying NLTE corrections, highlighting the critical role of NLTE abundance determinations. By comparing these measurements with Galactic chemical evolution (GCE) models, we find that the amount of NLTE correction does not require significant change of the parameters for Eu production in GCE models.