New Class of "Hypervelocity Stars" Discovered Escaping the Galaxy 150
Science_afficionado writes "Astronomers have discovered a surprising new class of 'hypervelocity stars' that are moving at more than a million miles per hour, fast enough to escape the gravitational grasp of the Milky Way galaxy. The 20 hyper stars are about the same size as the sun and, other than their extreme speed, have the same composition as the stars in the galactic disk. The big surprise is that they don't seem to come from the galaxy's center. The generally accepted mechanism for producing hypervelocity stars relies on the extreme gravitational field of the supermassive black hole that resides in the galaxy's core."
Re:Maybe they're not stars.... (Score:4, Insightful)
Now if you find an inhabitable planet orbiting one of these stars let me know. That would be the mothership of all motherships.
Or really bad luck. Leaving the galactic plane would pretty much assure your species would never branch out beyond your own solar system.
3-body chaotic gravity assist (Score:5, Insightful)
One of the theories for the origin of these hypervelocity stars is 3-body chaotic gravity assist. When two bodies are entering a gravity assist trajectory around a third, very massive body, their interactions sometimes add up in such a way that one body falls into a tight orbit, and another is ejected at a hypervelocity. Given the number of ternary star systems in the galaxy, this looks like a plausible explanation.
There is even a paper suggesting we could build an interstellar starship from two asteroids [prescientmodels.com] (PDF, 10 pages) using this mechanism. It was written by Josef L Breeden and presented at the 100 Year Starship conference.