It's a good week for black hole news, even if it's been a little like reading off an interstellar rap sheet.
The first finding of note concerns a star that seems to be cruising at high speeds away from the Milky Way galaxy. Given the apparent age of the star, researchers have previously been puzzled as to where exactly it could have come from.
Now scientists at the Carnegie Institution for Science say the star, which is moving at the "hyperfast" speed of 1.6 million miles per hour, must have come from Large Magellanic Cloud, a Milky Way neighbor.
Based on the star's rotation, the researchers say it was likely part of a binary star system, in which one member of the pair was swallowed by a black hole. This luckier twin was shot into intergalactic space with incredible velocity.
The second bit of news comes from supercomputing modeling done by researchers at the University of California at Santa Cruz, Jacobs
University in Germany, and the Oak Ridge National Laboratory.
They're working with the idea of mid-sized black holes – bigger than those created by the collapse of a single ordinary-sized star, but smaller than the monsters at the center of galaxies – the existence of which remains a matter of speculation.
The team modeled what would happen if a common white dwarf star wandered near one of these medium-sized black holes. White dwarfs commonly flare up into supernovas when they are able to suck gas from a companion star, but the team found that the presence of a nearby black hole could also reignite the star.
This kind of eruption should have a specific X-ray signature detectable by the Chandra X-ray Observatory, and may help prove the existence of the mid-sized black holes, the researchers say.
Hyperfast star proven to be alien [Carnegie Institution for Science]
Unusual supernovae may reveal intermediate-mass black holes in globular clusters [UCSC]
(Image: The Large Magellanic Cloud, photographed in infrared light by the Spitzer Space Telescope. Somewhere in there may lie an unseen black hole. Credit: NASA/JPL-Caltech/M. Meixner (STScI) & the SAGE Legacy
Team)
