000008047 001__ 8047
000008047 005__ 20260306090738.0
000008047 0247_ $$2DOI$$a10.3847/1538-4357/ae0b59
000008047 037__ $$aSCART-2026-0131
000008047 100__ $$aDixon, John D.
000008047 245__ $$aInvestigating Non-LTE Abundances of Neodymium in Metal-poor FGK Stars 
000008047 260__ $$c2025
000008047 520__ $$a The dominant site(s) of the r-process are a subject of current debate. Ejecta from r-process-enrichment events like kilonovae are difficult to directly measure, so we must instead probe abundances in metal-poor stars to constrain r-process models. This requires state-of-the-art non-LTE (NLTE) modeling, as LTE is a poor approximation for the low-opacity atmospheres of metal-poor giants. Neodymium (Nd) is a prominent r-process element detected in both near-infrared kilonova spectra and the spectra of metal-poor stars, so precise Nd stellar abundances are particularly needed to model kilonovae and constrain r-process sites. We thus constructed an Nd I/Nd II model atom to compute NLTE abundances in FGK metal-poor stars. We obtain A(Nd)⊙ = 1.44 ± 0.05, in agreement with the meteoritic value, when calibrating the model atom with a Drawin hydrogen collision factor of SH = 0.1. For a sample of metal-poor r-process-enhanced stars with observed optical and near-infrared Nd II lines, we find NLTE Nd corrections in the range −0.3 to 0.3 dex. Optical and UV lines have positive NLTE corrections, whereas H-band lines have negative corrections. Additionally, we compute a large grid of NLTE corrections for 122 Nd II spectral lines ranging from the UV to the H band, for stellar parameters of typical metal-poor FGK dwarfs and giants with −3 ≤ [Fe/H] ≤ −1 and −2 ≤ A(Nd) ≤ 2. Within this grid, we find NLTE corrections ranging from −0.3 to +0.5 dex. Deviations from LTE are found to be strongest for blue lines with low excitation potentials in the most metal-poor giants.
000008047 536__ $$aBELSPO/$$cFED-tWIN Prf-2020-033 BISTRO/$$fFED-tWIN Prf-2020-033 BISTRO
000008047 594__ $$aNO
000008047 6531_ $$aF stars
000008047 6531_ $$aStellar abundances
000008047 6531_ $$aG stars
000008047 6531_ $$aK stars
000008047 6531_ $$aStellar atmospheres
000008047 6531_ $$aChemical abundances
000008047 6531_ $$aAtomic data
000008047 700__ $$aEzzeddine, Rana
000008047 700__ $$aLi, Yangyang
000008047 700__ $$aMerle, Thibault
000008047 700__ $$aBautista, Manuel
000008047 700__ $$aGuo, Yanjun
000008047 773__ $$c20$$n1$$pThe Astrophysical Journal$$v994$$y2025
000008047 8560_ $$fthibault.merle@ksb-orb.be
000008047 85642 $$ahttps://iopscience.iop.org/article/10.3847/1538-4357/ae0b59
000008047 85642 $$ahttps://arxiv.org/abs/2509.22811
000008047 8564_ $$s5631805$$uhttps://publi2-as.oma.be/record/8047/files/Dixon_2025_ApJ_994_44.pdf
000008047 8564_ $$s10333$$uhttps://publi2-as.oma.be/record/8047/files/Dixon_2025_ApJ_994_44.gif?subformat=icon$$xicon
000008047 8564_ $$s25273$$uhttps://publi2-as.oma.be/record/8047/files/Dixon_2025_ApJ_994_44.jpg?subformat=icon-180$$xicon-180
000008047 905__ $$apublished in
000008047 980__ $$aREFERD