2025ApJ...991..112H

Based on the high-resolution and high signal-to-noise ratio near-ultraviolet spectra from the ESO VLT 8.2 m Kueyen telescope, we investigate the abundances of palladium (Pd) and silver (Ag) in a sample of 27 extreme metal-poor stars. The metallicity range of our sample stars is from ∼-2.2 to ∼-3.66 dex, and they are crucial for understanding the formation and evolution of weak r-process elements in our early Galaxy. The stellar atmospheric parameters, including effective temperature (T_eff), surface gravity (log g), metallicity ([Fe/H]), and microturbulence (ξ_t) are derived using the spectroscopic method, and the nonlocal thermodynamic equilibrium effects for both Fe I and Fe II lines have been considered when determining the iron abundance. Our results show that both [Pd/Fe] and [Ag/Fe] exhibit flat trends with metallicities between -0.7 and -3.0 dex, with an increasing scatter at lower metallicities. This study also finds a clear correlation between [Ag/H] and [Pd/H], indicating that both elements likely share a similar nucleosynthetic origin.