Recent observational advances, such as Gaia DR3 GSP-Spec, have highlighted
the potential of chemical abundances in tracing and revealing the structure of
spiral arms. Building on these studies, we aim to trace the Milky Way’s inner
spiral arms using chemical abundance data from the Gaia-ESO Survey (GES). By
mapping over-densities in [Fe/H] et [Mg/Fe], we seek to identify spiral arms
in both radial and vertical planes, detect substructures, and compare our
results with recent Galactic chemical evolution models. We used chemical
abundance data from the Gaia-ESO Survey to create spatial maps of [Fe/H],
[Mg/H], et [Mg/Fe] excess across the Galactic inner disc. We compared our
results with the spiral arm models proposed by Spitoni et al. (2023) et
Barbillon et al. (2024). For the first time, the inner spiral arms were
revealed using chemical abundance patterns. We detected [Fe/H] enhancements and
[Mg/Fe] under-abundances that consistently trace the Scutum and Sagittarius
arms. A connecting spur between these arms is observed in the [Mg/H] plane. The
alignment between our observations and the results of our 2D chemical evolution
models reinforces the significance of spiral arm transits in driving both
azimuthal and radial variations in chemical abundances. Our results confirm
that spiral arms can be traced using stellar chemical abundances with GES data,
providing a new perspective on the structure of the inner Galaxy. The
consistency between enhanced [Fe/H] and lower [Mg/Fe] ratios, as observed in
previous studies, further strengthens the reliability of our findings. The
observed spur, bifurcation, and vertical substructures align well with recent
models and studies, indicating that chemical maps can significantly contribute
to our understanding of Galactic spiral arms.

Cet article explore les excursions dans le temps et leurs implications.

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