I just came across a Scientific American article that I thought participants here might find interesting:

“[…] HIP 13044 b is the first verifiable exoplanet of extragalactic origin. […] HIP 13044 belongs to the Helmi stream, a population of stars that stretches through the Milky Way with similar, unusual orbits and compositions. The Helmi stream was determined in 1999 to have originated in a small galaxy, similar to the Sagittarius dwarf galaxy, that was cannibalized by the larger Milky Way. Later work found that the ingested galaxy must have been devoured six billion to nine billion years ago.”
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