New Insights into Metal-Poor Stars from the R-Process Alliance's Latest Data Release

The R-Process Alliance has released its fifth data set focusing on the search for R-Process-Enhanced Metal-poor Stars in the Galactic Halo, utilizing the Gran Telescopio Canarias (GTC). This release includes detailed chemical abundances for 41 extremely metal-poor halo stars, with metallicities as low as [Fe/H] = -3.3. The researchers employed high-resolution spectroscopy with the HORuS spectrograph to analyze these stars, which are faint, reaching down to a magnitude of V = 15.8.

Key findings from this data release include the identification of five Carbon-Enhanced Metal-Poor (CEMP) stars, one limited-R process star, three R-I stars, and four R-II stars. Additionally, six stars were classified as magnesium-poor. Notably, one star was identified as potentially originating from a globular cluster, which supports the hypothesis of a metallicity floor for globular cluster abundances.

The study further investigates the contributions of various nucleosynthesis channels in progenitor supernovae by analyzing the abundances of iron-peak and alpha-elements. The research highlights differences in the abundance trends of neutron-capture elements such as Strontium (Sr), Barium (Ba), and Europium (Eu) among R-I and R-II stars, providing insights into their nucleosynthesis sites and subsequent evolution.

This data release contributes to a deeper understanding of the chemical evolution of the Milky Way and the origins of heavy elements in the universe. The findings are expected to have significant implications for the field of astrophysics, particularly in the study of stellar populations and nucleosynthesis processes.

For more details, the full paper can be accessed at arXiv:2408.03731.