Free Astronomy Magazine July-August 2024

39 JULY-AUGUST 2024 ASTRO PUBLISHING Led by Carlos Saffe of the Institute of Astronomical, Earth and Space Sciences (ICATE-CONICET) in Ar- gentina, the team used the Gemini South telescope in Chile, one half of the International Gemini Observa- tory, supported in part by the U.S. National Science Foundation and operated by NSF NOIRLab. With the new, precise Gemini High Resolu- tion Optical SpecTrograph (GHOST) the team studied the different wavelengths of light, or spectra, given off by a pair of giant stars, which revealed significant differ- ences in their chemical make-up. “GHOST’s extremely high-quality spectra offered unprecedented res- olution − said Saffe − allowing us to measure the stars’ stellar parame- ters and chemical abundances with the highest possible precision.” These measurements revealed that one star had higher abundances of heavy elements than the other. To disentangle the origin of this dis- crepancy, the team used a unique approach. Previous studies have proposed three possible explanations for ob- served chemical differences be- tween binary stars. Two of them involve processes that would oc- cur well into the stars’ evolution: atomic diffusion, or the settling of chemical elements into gradient lay- ers depending on each star’s tem- perature and surface gravity; and the engulfment of a small, rocky