Joint Astrophysical Colloquium
Challenging the Canon: Evidence for Young, Metal-Rich RR Lyrae Stars
Valentina D'Orazi (Università Tor Vergata)
Thursday 30/04/2026 @ 11:30, Sala Antonio Sollima (IV piano Battiferro)
RR Lyrae stars have long served as fundamental pillars of astrophysics, acting as precise standard candles and tracers of the oldest, most metal-poor structures in the Universe. Canonical stellar evolution models dictate that these core-helium-burning pulsators emerge only from ancient populations (ages older than ~9–10 Gyr) with low metallicity ([Fe/H] < -0.5). However, a growing body of kinematic, spectroscopic and photometric evidence is challenging this traditional paradigm, suggesting the existence of a distinct population of RRLs that are surprisingly young and metal-rich.In this seminar, I will review the emerging tension between canonical theory and recent observations. This paradigm shift has profound implications for how we use these stars to map the formation and evolutionary history of the Milky Way.