Located 2.5 million light-years away, the Andromeda galaxy appears as a faint, spindle-shaped object to the naked eye. However, NASA’s Hubble Space Telescope has been studying its satellite galaxies in unprecedented detail. The telescope’s observations of over 1,000 orbits have built a precise 3D mapping of dwarf galaxies surrounding Andromeda.
The study published in The Astrophysical Journal reveals a markedly different ecosystem from those found around the Milky Way. This suggests that Andromeda’s history has been shaped by major mergers and interactions with other galaxies. One possible explanation is a massive merger with another big galaxy, which could have led to its diverse dwarf galaxy population.
Hubble’s observations show that the duration for satellite galaxies to form new stars depends on their mass and proximity to Andromeda. The study also highlights an unusual arrangement of half of the satellite galaxies, all orbiting in the same direction, a configuration not fully understood by astronomers.
The brightest companion galaxy, Messier 32 (M32), may be the remnant core of a larger galaxy that collided with Andromeda. Its population of older stars and evidence of recent star formation provide insights into the galaxy’s history.
Future Hubble observations will enable scientists to reconstruct the motions of all 36 dwarf galaxies in the Andromeda ecosystem billions of years into the past, offering a bird’s-eye view of this galactic “ecosystem.” The study contributes to our understanding of the evolution of small galaxies and challenges existing theories about galaxy formation.
Source: https://science.nasa.gov/missions/hubble/nasas-hubble-provides-birds-eye-view-of-andromeda-galaxys-ecosystem