What is the name of the faint stream of stars from a disrupted dwarf galaxy in the Milky Way's halo?

The faint stream of stars from a disrupted dwarf galaxy in the Milky Way’s halo is the Sagittarius Stream.

This enormous, elongated structure consists of stars tidally stripped from the Sagittarius Dwarf Spheroidal Galaxy as that small satellite has orbited and merged with the Milky Way over billions of years. The debris stretches along the dwarf galaxy’s path, wrapping around the Milky Way in an orbit that comes close to the Galactic poles.

The stream was proposed in 1995 from the unusual distribution of globular clusters. Its stellar structure was identified in the early 2000s using surveys including 2MASS and the Sloan Digital Sky Survey. Later observations revealed that it has two prominent branches, reflecting the complex geometry of the disruption and the Milky Way’s gravitational field.

The Sagittarius Stream is not the same as the Magellanic Stream, which is primarily a stream of gas associated with the Magellanic Clouds. The Orphan Stream is another stellar stream with a different origin. Stellar streams such as Sagittarius preserve evidence of how galaxies grow by absorbing smaller companions.