Carlberg, R. G., Harvey B. Richer, Alan W. McConnachie, Mike Irwin, et al. 2011. "Density Variations in the NW Star Stream of M31." The Astrophysical Journal 731:124.
The Pan Andromeda Archeological Survey (PAndAS) CFHT Megaprime survey of the M31-M33 system has found a star stream which extends about 120 kpc NW from the center of M31. The great length of the stream, and the likelihood ...