Stars: Watch out. There's a black hole out there, waiting to eat you alive.
You've heard of black holes. They are places in space where the gravity is so intense, nothing can get out, not even light. Hence, the term "black hole." We know they exist, but we can't actually see them, because they swallow all the light around them. So, the best way to spot them is to look for objects that are acting like they are near a black hole. Say, a star.
When a star gets near a black hole, it's sucked in by what are called "tidal forces," which can rip that star into pieces. That process is called, appropriately, a "tidal disruption," which is kind of an understatement. Nothing is quite so disruptive as getting pulled apart. When the stars are clobbered in this way, it causes a solar flare that can last for years, giving astronomers evidence that the star was there.
This week, a team of astronomers from the University of Maryland announced that members have observed a tidal disruption in a galaxy 290 million light years from Earth. It's the biggest tidal disruption they've seen in a decade. They gave it the foreboding name ASASSN-14li.
The "assassin" was spotted because of its distinctive X-ray gases. The X-rays are created when pieces of the star are pulled into the black hole, heat up, and bubble out in X-ray gases. Once the scientists had identified the X-rays, they tapped colleagues at NASA and the European Space Agency to get a clearer picture of what was going on.
"We have seen evidence for a handful of tidal disruptions over the years and have developed a lot of ideas of what goes on," said lead author Jon Miller, a professor of astronomy at the University of Michigan, in a press release. "This one is the best chance we have had so far to really understand what happens when a black hole shreds a star."
Although we think of black holes as eating everything in sight, they actually do have a limit to what they can swallow, so they end up repelling some of the debris headed their way. This includes gases and winds that are prime for studying.
"The black hole tears the star apart and starts swallowing material really quickly, but that's not the end of the story," said study coauthor Jelle Kaastra, an astronomer at the Institute for Space Research in the Netherlands. "The black hole can't keep up that pace so it expels some of the material outwards."
By studying these black hole survivors, the scientists can get a better picture of what actually happens in the mysterious death traps. The surviving gases are, in a sense, ambassadors for the pieces of planetary debris that will never return.
The research is described in a paper published in the Oct. 22 issue of the journal Nature.
