The merger that led to the formation of the Milky Way’s inner stellar halo and thick disk

The merger that led to the formation of the Milky Way’s inner stellar halo and thick disk

The merger that led to the formation of the Milky Way’s inner stellar halo and thick disk, Published online: 31 October 2018; doi:10.1038/s41586-018-0625-x

A galaxy slightly larger than the Small Magellanic Cloud merged with the Milky Way about 10 billion years ago, thickening the ancient disk and forging the Galaxy’s inner halo.