Gaia Sausage

Etymology
. From being discovered by the, a European Space Agency space telescope that maps the stars of the Milky Way, and forming a sausage-shaped plot in velocity-space.

Proper noun

 * 1)  A stellar population within the  that forms a sausage-shaped plot in velocity-space, which is thought to originate from a galaxy merger 10 billion years ago, with the  galaxy, composing mostly Milky Way s.