2025MNRAS.540.3850H

Elemental abundances hold important information about the star formation history in the Galactic Centre. The thermal X-ray spectra of certain stars can provide a robust probe of elemental abundances, mainly through the presence of K-shell emission lines. In this work, based on deep archival Chandra observations, we obtain X-ray measurements of five heavy elements (Si, S, Ar, Ca, and Fe) for three sources in the Arches cluster, one source in the Quintuplet cluster, as well as a field source known as Edd 1, which are all probable Wolf-Rayet (WR) stars exhibiting a high-quality X-ray spectrum. A two-temperature non-equilibrium ionization plasma model is employed for the spectral fit, taking into account light element compositions characteristic of WR star winds, which is substantially depleted in hydrogen but enriched in nitrogen and/or carbon. It is found that the Arches and Quintuplet WR stars share similar abundances of Si, S, and Ar, while they exhibit distinct Ca and Fe abundances, which may be understood as due to dust depletion of the latter two elements in Quintuplet. The observed near-solar or sub-solar metallicity of the WR star winds can be naturally understood as the result of nucleosynthesis and internal mixing of the parent star, which have a supersolar initial metallicity as expected for the Galactic Centre in general. Implications of our findings on the origin of the young star clusters and isolated massive stars in the Galactic Centre, as well as the elemental composition of the accretion flow on to Sgr A*, are addressed.