Long, faint trails of stars that are stripped away from smaller galaxies or star clusters due to the powerful gravitational forces of larger galaxies. These streams form when a dwarf galaxy or globular cluster ventures too close to a massive galaxy like the Milky Way, causing tidal forces to pull it apart.
Key points:
- Tidal streams are evidence of galactic interactions and mergers.
- They help astronomers map the distribution of dark matter in galaxies, since their shapes trace the gravitational field.
- Examples in the Milky Way include the Sagittarius Stream and the Magellanic Stream, formed from dwarf galaxies being torn apart.
- These streams show that galaxy growth happens through galactic cannibalism, where large galaxies absorb smaller ones over time.
Tidal streams act like cosmic fingerprints of past interactions, providing clues about the Milky Way’s history and structure.