"flung from the Way's Galactic Center"
Is that because they're moving way too fast?
An artificial neural network has detected rare super-fast stars zipping through the Milky Way – by crunching piles of data collected by the European Space Agency’s Gaia probe. Hypervelocity stars (HVSes) are flung from the Way's Galactic Center and can reach speeds faster than our galaxy's escape velocity. Only 20 unbound …
This classification task seems very straightforward.
Decision trees not hip enough?
It's surprising there aren't more hyper-velocity stars, I used to have a RISC OS screen saver which simulated galaxies colliding and many stars used to escape before the galaxies coalesced. But then again it might not have been a very accurate simulation on a 200MHz Strong ARM.
The Milky Way has already collided with several smaller galaxies, and is in the process of colliding with the large and small Magellanic clouds (small galaxies). Eventually the really biggy will be in 4bn years when it comes together with the massive Andromeda galaxy.