Fraser’s postdoctoral research focuses on what are known as the missing mixing problems in red giant branch (RGB) stars. When RGB stars are formed, they contain a certain amount of lithium. But these lithium levels can change over time. Based on a theoretical understanding of these stars, scientists thought that lithium would be lost from layers deep within these stars as they age, but that lithium levels on the star’s surface would remain fairly constant. However, the data shows that lithium is lost from the surface of these stars, a finding that continues to puzzle researchers.