Observational constraints on the origin of the elements. X. Combining NLTE and machine learning for chemical diagnostics of 4 million stars in the 4MIDABLE-HR survey

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Auteurs principaux: Storm, Nicholas, Bergemann, Maria, Różański, Tomasz, Ksoll, Victor F., Bensby, Thomas, Traven, Gregor, Kordopatis, Georges, Church, Ross P., Jian, Mingjie, Sun, Weijia, Guiglion, Guillaume, Tautvaišienė, Gražina
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Publié: 2025
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author Storm, Nicholas
Bergemann, Maria
Różański, Tomasz
Ksoll, Victor F.
Bensby, Thomas
Traven, Gregor
Kordopatis, Georges
Church, Ross P.
Jian, Mingjie
Sun, Weijia
Guiglion, Guillaume
Tautvaišienė, Gražina
author_facet Storm, Nicholas
Bergemann, Maria
Różański, Tomasz
Ksoll, Victor F.
Bensby, Thomas
Traven, Gregor
Kordopatis, Georges
Church, Ross P.
Jian, Mingjie
Sun, Weijia
Guiglion, Guillaume
Tautvaišienė, Gražina
contents We present the 4MOST-HR resolution Non-Local Thermal Equilibrium (NLTE) Payne artificial neural network (ANN), trained on $404\,793$ new FGK spectra with 16 elements computed in NLTE. This network will be part of the Stellar Abundances and atmospheric Parameters Pipeline (SAPP), which will analyse 4 million stars during the five year long 4MOST consortium 4: 4MOST MIlky way Disc And BuLgE High-Resolution (4MIDABLE-HR) survey. A fitting algorithm using this ANN is also presented that is able to fully-automatically and self-consistently derive both stellar parameters and elemental abundances. The ANN is validated by fitting 121 observed spectra of low-mass FGKM type stars, including main-sequence dwarf, subgiant and giant stars down to [Fe/H] $\approx -3.3$ degraded to 4MOST-HR resolution of $R\approx20\,000$, and comparing the derived abundances with the output of the classical radiative transfer code TSFitPy. We are able to recover all 18 elemental abundances with a bias~$<0.13$ and spread~$<0.16$\,dex, although the typical values are $<0.09$ dex for most elements. These abundances are compared to the OMEGA+ Galactic Chemical Evolution model, showcasing for the first time, the expected performance and results obtained from high-resolution spectra of the quality expected to be obtained with 4MOST. The expected Galactic trends are recovered, and we highlight the potential of using many chemical elements to constrain the formation history of the Galaxy.
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id arxiv_https___arxiv_org_abs_2512_15888
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Observational constraints on the origin of the elements. X. Combining NLTE and machine learning for chemical diagnostics of 4 million stars in the 4MIDABLE-HR survey
Storm, Nicholas
Bergemann, Maria
Różański, Tomasz
Ksoll, Victor F.
Bensby, Thomas
Traven, Gregor
Kordopatis, Georges
Church, Ross P.
Jian, Mingjie
Sun, Weijia
Guiglion, Guillaume
Tautvaišienė, Gražina
Solar and Stellar Astrophysics
Astrophysics of Galaxies
We present the 4MOST-HR resolution Non-Local Thermal Equilibrium (NLTE) Payne artificial neural network (ANN), trained on $404\,793$ new FGK spectra with 16 elements computed in NLTE. This network will be part of the Stellar Abundances and atmospheric Parameters Pipeline (SAPP), which will analyse 4 million stars during the five year long 4MOST consortium 4: 4MOST MIlky way Disc And BuLgE High-Resolution (4MIDABLE-HR) survey. A fitting algorithm using this ANN is also presented that is able to fully-automatically and self-consistently derive both stellar parameters and elemental abundances. The ANN is validated by fitting 121 observed spectra of low-mass FGKM type stars, including main-sequence dwarf, subgiant and giant stars down to [Fe/H] $\approx -3.3$ degraded to 4MOST-HR resolution of $R\approx20\,000$, and comparing the derived abundances with the output of the classical radiative transfer code TSFitPy. We are able to recover all 18 elemental abundances with a bias~$<0.13$ and spread~$<0.16$\,dex, although the typical values are $<0.09$ dex for most elements. These abundances are compared to the OMEGA+ Galactic Chemical Evolution model, showcasing for the first time, the expected performance and results obtained from high-resolution spectra of the quality expected to be obtained with 4MOST. The expected Galactic trends are recovered, and we highlight the potential of using many chemical elements to constrain the formation history of the Galaxy.
title Observational constraints on the origin of the elements. X. Combining NLTE and machine learning for chemical diagnostics of 4 million stars in the 4MIDABLE-HR survey
topic Solar and Stellar Astrophysics
Astrophysics of Galaxies
url https://arxiv.org/abs/2512.15888