The Helmi stream is a stellar stream of the Milky Way Galaxy. It started as a dwarf galaxy, now absorbed by the Milky Way as a stream. It was discovered in 1999, is formed of old stars deficient in heavy elements and has a mass of 10 to 100 million solar masses. It was absorbed by the Milky Way some 6 to 9 billion years ago.[1]
The Helmi stream is host to the first discovered planet of extragalactic origin, HIP 13044 b, around the star HIP 13044.[2]