"Hypervelocity stars" refer to stars that move extremely fast through space. They travel at such high speeds that they are able to escape the gravitational pull of their home galaxies. Full definition
The star, dubbed HE 0437 - 5439, is an early - type star and one of ten so - called hypervelocity stars so far found speeding away from the Milky Way. (carnegiescience.edu)
There are alternative scenarios, but none explains why most of the 20 or so hypervelocity stars found so far are all in the same area of sky, in the Leo and Sextans constellations. (sciencemag.org)