This story may seem like science fiction, but Hubble astronomers say it is the most likely scenario for the creation of a so-called hypervelocity star, known as HE 0437-5439. It is one of the fastest ever detected with a speed of 1.6 million mph. Hubble observations confirm that the stellar speedster hails from the Milky Way's core, settling some confusion about the star's original home. Most of the roughly 16 known hypervelocity stars, all discovered since 2005, are thought to be exiles from the heart of our galaxy. But this Hubble result is the first direct observation linking such a star to an origin in the center of the galaxy.
"Using Hubble, we can for the first time trace back to where the star came from by measuring the star's direction of motion on the sky," said astronomer Warren Brown of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass. "Our measurements point directly to the Milky Way center." Brown, a member of the Hubble team that observed the star, is the lead author on a paper about the finding published online July 20 in the Astrophysical Journal Letters. Brown said, "These exiled stars are rare in the Milky Way's population of 100 billion stars. For every 100 million stars in the galaxy, there lurks one hypervelocity star."