Simulated observations of heavy elements with CUBES

TL;DR

This study assesses the potential of the CUBES instrument for near-UV spectroscopy to accurately measure neutron-capture element abundances in very metal-poor stars, demonstrating significant observational improvements.

Contribution

It presents a simulation-based evaluation of CUBES capabilities for detecting and estimating abundances of specific heavy elements in faint stars, highlighting its enhanced sensitivity.

Findings

CUBES can recover Ge and Hf abundances with ±0.1 dex accuracy in 4-hour exposures.

CUBES enables observations of targets 2-3 magnitudes fainter than current capabilities.

Simulations suggest possible upper limits for Bi and U lines in challenging observational conditions.

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 {\AA} and Hf II 3400 and 3719 {\AA} 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 $\pm$0.1 dex for Ge for U $\sim$ 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 {\AA} and U II 3860 {\AA} lines (for U $\sim$ 14.25 and 16mag., respectively), finding that simulated 4hr exposures should provide upper limits to these observationally challenging lines.