Seminar by Cecilia Mateu, Centro de Investigaciones de Astronomía, Venezuela
RR Lyrae stars have long been seen as unequivocal tracers of old (>10 Gyr) metal-poor ([Fe-H]<-0.5) stellar populations. First, because these populations are where they are most easily found; but also because, according to canonical stellar evolution models for isolated stars, these are the only populations where RR Lyrae should exist. New independent results, however, are challenging this view and pointing at the existence of intermediate-age RR Lyrae, only a few Gyrs old (Sarbadhicary et al. 2021, Iorio et al. 2021). In this seminar I will discuss our work using RR Lyrae stars as canonical tracers of structure and substructure of the thick disc and halo, as well as ongoing projects looking for direct evidence of the existence of RR Lyrae in intermediate-age populations and their possible formation channels via binary interactions.
Host: Kathryn Johnston