Overview
- A team led by Davide Sestito used Gaia astrometry to select candidates and followed up with high-resolution spectroscopy at the Canada-France-Hawaii Telescope to study the stars’ motions and chemistry.
- The group consists of 20 very metal-poor stars located roughly 7,000 light-years from the Sun and unusually close to the Galaxy’s disk compared with where such ancient stars are normally found.
- All 20 stars show very low amounts of heavy elements and matching abundance patterns that imply ages of more than 10 billion years and a common origin.
- Authors interpret the group as likely remnants of a single metal-poor dwarf galaxy accreted early in the Milky Way’s history, but they caution that precise ages and orbital histories remain uncertain and need follow-up modelling and observation.
- Because metal-poor stars are rare in the crowded, dusty disk, this finding shows merger debris can be embedded inside the disk and will push astronomers to combine more Gaia data, spectroscopy, and simulations to pin down the progenitor’s mass and orbit.