Hypervelocity stars

In 2014, astronomers discovered that 18 giant blue stars were being ejected out of our galaxy and they were unsure how the stars were being propelled. Unlike most other known hypervelocity stars, these are not exiting after interacting with the black hole in the heart of the galaxy. Leaving the galaxy takes a phenomenal amount of energy. Stars must reach speeds 1 million mph (1.6 million km/h) faster than the 600,000 mph (970,000 km/h) at which objects already speed around the Milky Way.