A 3D Chemical Map of the Milky Way's Spiral Structure
Mapping the Milky Way spiral arms in the vertical direction remains a challenging task that has received little attention.
We analyse a sample of young giant stars from Gaia DR3 and use their metallicity distribution to produce a 3D metallicity
excess map. The map shows signatures of the spiral arms, whose vertical height vary across the Galactic disc, reaching up
to 400 pc in amplitude and exhibiting vertical asymmetries with respect to the midplane. Specifically, the Perseus arm
displays a high vertical asymmetry consistent with the Galactic warp.
We find evidence of a metal-rich stellar structure that undulates nearly in phase with the Radcliffe Wave. This new structure
is larger and extends beyond the Radcliffe Wave, reaching vertical amplitudes of 270 pc and extending for at least 4 kpc in length.
We confirm that for at least half of its length this Extended Radcliffe Wave is the inner edge of the Local Arm. The finding of a
metal-rich stellar counterpart of the Radcliffe Wave shows that mapping the three-dimensional metallicity distribution of young
stellar populations reveals key information about the structures and chemical enrichment in the Galactic disc.
See Martinez-Medina et al. 2025
➤ Click here to explore the interactive 3D maps used in the paper

