Hidden Clusters in the Dust: Using RR Lyrae Stars to Uncover the Milky Way’s Missing Building Blocks
The paper presents a search for hidden globular clusters in the Milky Way’s dusty plane and bulge using RR Lyrae stars as tracers of old stellar populations. By combining Gaia and near-infrared data with a carefully calibrated clustering algorithm, the authors recover known clusters and identify several compact RR Lyrae groups that may represent previously undiscovered or disrupted clusters.
Tracing Ancient Mergers in the Heart of the Milky Way: RR Lyrae Stars and the Gaia-Enceladus/Sausage in the Inner Stellar Halo
Kunder et al. study RR Lyrae stars in the Milky Way’s inner halo to trace remnants of the ancient Gaia-Enceladus/Sausage merger. They find about 6-9% of these stars show motions and metallicities consistent with GES, less than in the solar neighborhood. Their results match simulations showing GES debris is less concentrated near the Galactic center.
Exploring the Galactic Halo with RR Lyrae Stars
Cabrera Garcia et al. analyze over 135,000 RR Lyrae stars to study the Milky Way’s halo structure. They confirm the existence of inner and outer halo components and identify 97 dynamically tagged groups (DTGs) using motion-based clustering. Many DTGs align with known galactic substructures, such as Gaia-Sausage-Enceladus and the Helmi Stream, highlighting past galaxy mergers. Their findings reinforce the idea that the Milky Way’s halo formed through multiple accretion events.