Orbital Clustering Identifies the Origins of Galactic Stellar Streams

Understand

The origins of most stellar streams in the Milky Way are unknown.

• With improved proper motions provided by Gaia EDR3, we show that the orbits of 23 Galactic stellar streams are highly clustered in orbital phase space.
• Based on their energies and angular momenta, most streams in our sample can plausibly be associated with a specific (disrupted) dwarf galaxy host that brought them into the Milky Way.
• For eight streams we also identify likely globular cluster progenitors (four of these associations are reported here for the first time).