“Heracles” –The Ancient Invader that Seeded the Milky Way’s Halo with Alien Stars

Milky Way Halo

 

Astronomers have excavated a galactic tomb: new discoveries, the most recent by the Sloan Digital Sky Surveys’ Apache Point Observatory Galactic Evolution Experiment (APOGEE) that observes the “archaeological” record embedded in hundreds of thousands of stars to explore the assembly history and evolution of the Milky Way Galaxy, have unveiled a stunning picture of our home galaxy’s successive mergers with neighboring galaxies.

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