The Milky Way Galaxy contains billions of stars. Though the vast majority of these are bound to the galaxy by gravity, astronomers have found a few tens of stars that are not orbiting but instead fleeing our galaxy at extreme speeds. These hypervelocity stars have intrigued researchers for years, and now a new mysterious player has entered the game. LAMOST-HVS, the closest of these fast-moving stars to our sun, has an origin story markedly different from the way we believed these stars get their kick out of the Milky Way.
In a study led by researchers from the University of Michigan and published March 12 in the Astrophysical Journal, astronomers used data from the Magellan telescope in Chile and the European Space Agency’s Gaia satellite to wind back the clock and trace the trajectory of LAMOST-HVS, an 8.3-solar-mass star zipping away from the galaxy at more than 350 miles per second (568 kilometers per second). LAMOST-HVS is the closest hypervelocity star to the sun, and researchers estimate it was sent on its way by an event that occurred 33 million years ago. But that event, it seems, was different from the single origin astronomers have developed for how hypervelocity stars are ejected from the galaxy, suggesting there may be more than one way to kick a star out of the Milky Way.
