Nov 14, 2019
Ejected Star: How fast is fast?
Posted by Philip Raymond in categories: astronomy, science, space

Earlier today, Genevieve O’Hagan updated Lifeboat readers on this week’s momentous event in Astronomy. At least, I find it fascinating—and so, I wish to add perspective…
30 years ago, astronomer Jack Hills demonstrated the math behind what has become known as the “Hills Mechanism”. Until this week, the event that he described had never been observed.* But his peer astronomers agreed that the physics and math should make it possible…
Hills explained that under these conditions, a star might be accelerated to incredible speeds — and might be even flung out of its galaxy:
- Suppose that a binary star passes close to a black hole, like the one at the center of our galaxy
- The pair of self-orbiting stars is caught up in the gravity well of a black hole, but not sucked in
If conditions are right, one star ends up orbiting the back hole while the other is jettisoned at incredible speed, yet holding onto its mass and shape. All that energy comes from the gravity of the black hole and the former momentum of the captured star. [20 sec animation] [continue below]