Overview
- A Nature Astronomy paper published Aug. 17 reports that a team led by Davide Massari identified a distinct population of globular clusters that trace a dwarf galaxy, which they name Low‑energy–Kraken‑Heracles (LKH), merged into the Milky Way about 11.8 billion years ago.
- The result is based on precise ages and metallicities for 39 inner‑Galaxy globular clusters measured with Hubble imaging and Gaia astrometry that separate those clusters into three clear families.
- The researchers estimate LKH had roughly 5×10^8 solar masses in stars and deposited most of its stars, interstellar gas and dark matter into the central ~20,000 light‑years of the Milky Way.
- The LKH merger predates the better‑known Gaia–Sausage–Enceladus event by about 1.8–2 billion years, a timing that requires modelers to update simulations of the Galaxy’s early growth and dynamical history.
- Teams plan deeper inner‑Galaxy surveys, targeted spectroscopy and new simulations to map LKH’s stellar remnants, test its effects on early star formation and quantify how much it reshaped the infant Milky Way.