Mapping the Metallic Hearts and Ancient Halos of Dwarf Galaxies
Tau et al. study 17 simulated dwarf galaxies to track how their stars’ ages and metallicities change from the center to the stellar halo. They find universal negative metallicity gradients, frequent U-shaped age profiles driven by in-situ stars, and strong links between halo properties and the timing of satellite accretion. Overall, dwarf stellar halos preserve clear signatures of each galaxy’s unique merger and star-formation history.
Tracing the Galactic Past: Chemical Clues from the Milky Way’s Faint Companions
Cheng Xu and collaborators used APOGEE data to study the chemical makeup of four dwarf galaxies orbiting the Milky Way. They found that galaxy mass influences how elements like magnesium and iron evolve over time, with larger galaxies retaining alpha elements longer. In Fornax, they discovered nitrogen-rich stars likely from disrupted globular clusters, offering clues about early star formation and galactic evolution.
Ghosts and Companions of the Milky Way: What Dwarf Galaxies Tell Us About Galaxy Formation
Grimozzi et al. used simulations to compare gas in disrupted and surviving dwarf galaxies around the Milky Way. They found that disrupted dwarfs, accreted earlier, have lower metallicity and higher [Mg/Fe], reflecting bursty star formation. These chemical differences reveal how timing influences galaxy evolution in the Milky Way’s past.