A group of researchers led by Warren Brown of the Smithsonian Astrophysical Observatory in Cambridge, Massachusetts, has discovered a number of stars with high velocities that are being cast out of the Milky Way. Brown and his group discovered the first such star in 2005, and 20 more have followed. “These stars form a new class of astronomical objects,” said Brown, “exiled stars leaving the galaxy.”
These suns are obviously quite rare; astronomers believe the Milky Way may hold about 1,000 of them. The escape velocity for objects in the Milky Way is about 60 miles per second (100 km/sec), and these so-called hypervelocity stars are moving at speeds of about 600 miles per second (1,000 km/sec). Observationally, they are dim objects, mostly in the range of magnitude 18.5 to 20.5.
Astronomy’s great friend and astroimaging expert Anthony Ayiomamitis has captured some extraordinary photos of some of these stars, and is working in tandem with the SAO research team. I’m presenting two images of hypervelocity stars taken by Anthony here — you can read about his work in this area at the following links: http://www.perseus.gr/Astro-Star-HVS-02.htm, http://www.perseus.gr/Astro-Star-HVS-04.htm.
Hats off to Anthony for imaging such amazingly dim and distant stars with such great and special significance!
HVS 2 in Ursa Major
HVS 4 in Cancer