Discoveries of Hypervelocity Stars and What They Tell Us About the Galactic Center

Hypervelocity stars leaving the Galaxy at ~1000 km/s are a natural consequence of a massive black hole in a dense stellar environment. In 2005 we discovered the first such hypervelocity star (HVS): a 3 solar mass B star, similar to stars seen in the Galactic Center, but 110 kpc distant and moving away at over 700 km/s. Our follow-up survey has resulted in seven further HVS discoveries plus evidence for a class of HVSs on bound trajectories. We discuss how the observed anisotropic spatial distribution of HVSs is linked to their ejection mechanism. HVSs place quantitative constraints on the types of stars in the Galactic Center, and the history of stellar interactions with the central black hole.