Ella Xi Wang (Stockholm University) -- Spectroscopic Measurements of Lithium in Late-type Stars

Spectroscopic Measurements of Lithium in Late-type Stars

Low mass stars retain the chemical imprint of the gas cloud they were born from. Therefore, stellar abundances provide insight into the evolution of stars and chemical elements throughout the life of galaxies, such as our own Milky Way. Galactic archaeology uses stars and their chemical fingerprints like fossils to trace cosmic history. Out of the known elements, lithium (Li) is a uniquely interesting element, produced in Big Bang Nucleosynthesis and cosmic ray spallation, and moderated in stellar evolution. Stellar abundances cannot be directly observed or measured, instead they must be inferred from models. I will discuss the most physically realistic radiative transfer (3D NLTE) models, how accurate they are compared to high fidelity observations, and how these models can be applied to large spectroscopic surveys to improve accuracy of abundances. Through this work, I measure the lithium abundance of the Sun, reject the second cosmological lithium problem, uncover the evolution of the Li-dip up the subgiant branch in field stars, and find a potential signal for planet engulfment.