Simulated observations of heavy elements with CUBES

Abstract

We investigate the feasibility of robust abundances for selected neutron-capture elements (Ge, Bi, Hf, U) from near-UV spectroscopy with the CUBES instrument now in development for the Very Large Telescope. We use the CUBES end-to-end simulator to synthesise observations of the Ge I 3039 Å and Hf II 3400 and 3719 Å lines in a very metal-poor star, using the well-studied star CS 31082-001 as a template. From simulated 4 hr exposures, we recover estimated abundances to ± 0.1 dex for Ge for U ∼ 14.25 mag., and for Hf for U = 18 mag. These performances neatly highlight the powerful gain of CUBES for near-UV observations of targets that are two-to-three magnitudes fainter than the existing observations of CS 31082-001 (U= 12.5 mag.). We also investigate the weak Bi I 3025 Å and U II 3860 Ålines (for U ∼ 14.25 and 16 mag., respectively), finding that simulated 4 hr exposures should provide upper limits to these observationally challenging lines.