Helmi stream

[2][3] The Helmi Stream discovery affirmed theories that the merging of galaxies played a significant role in creating the giant structures of the Milky Way galaxy.

[2] In 2024 a subdwarf of spectral type sdT4 was identified as a possible member of the Helmi stream.

The brown dwarf is called CWISE J155349.96+693355.2 has Vtan > 300 km/s and a poorly constrained radial velocity of +110 ±90 km/s.

[4] The Helmi stream was home to the first discovered planet purportedly of extragalactic origin, orbiting the star HIP 13044.

[1] Further analysis of radial velocity data failed to confirm the discovery.