The detailed chemical abundance patterns of accreted halo stars from the optical to infrared

Understand

Understanding the assembly of our Galaxy requires us to also characterize the systems that helped build it.

• In this work, we accomplish this by exploring the chemistry of accreted halo stars from the Gaia-Enceladus/Gaia-Sausage (GES) selected in the infrared from the Apache Point Observatory Galactic Evolution Experiment (APOGEE) Data Release 16.
• We use high resolution optical spectra for 62 GES stars to measure abundances in 20 elements spanning the $\alpha$, Fe-peak, light, odd-Z, and notably, the neutron-capture groups of elements to understand their trends in the context of and in contrast to the Milky Way and other stellar populations.
• Using these derived abundances we find that the optical and the infrared abundances agree to within 0.15 dex except for O, Co, Na, Cu, and Ce.