A Walk on the Retrograde Side (WRS) project II

The analysis is performed in comparison with the Gaia-Sausage-Enceladus (GSE) remnant, within the fully self-consistent and homogeneous framework established by the WRS project. We analyse high-resolution and high signal-to-noise ratio spectra obtained with UVES at VLT for 212 Red Giant Branch stars classified as candidate members of Thamnos and GSE, based on selections in the space of the integrals of motion.

We derive precise abundances for 16 atomic species. Compared to GSE, stars attributed to the Thamnos substructure are, on average, more metal-poor, yet most of them show relatively higher [X/Fe] abundance ratios in several elements, like Na, Mg, Al, Ca, Cu, Zn, as well as lower [Eu/Fe]. The majority of candidate Thamnos stars show chemical signatures more consistent with the in situ Milky Way halo rather than a typical low-mass accreted dwarf galaxy.