When a satellite galaxy gets too close to its massive central galaxy, the large galaxy’s gravity tears apart the satellite. Some of the galaxy’s stars merge with the larger galaxy. But for others, the massive galaxy flings the stars from the satellite — some at extreme speeds. According to astrophysicists Mario G. Abadi, Julio F. Navarro, Matthias Steinmetz, and Laura V. Sales, these stars could be the hypervelocity stars that astronomers have observed.
Getting a kick out of merging
A simulation shows how merging galaxies can fling stars to hypervelocities.