This artist’s impression illustrates what it might look like when a star gets too close to a black hole, where the star is being squeezed by the black hole’s strong gravitational pull. Some of the star’s matter is pulled in and swirls around the black hole, forming the disk seen in this image. In rare cases like this, jets of matter and radiation are ejected from the black hole’s poles. (ESO, M. Kornmesser via Reuters)
Estimated reading time: 3-4 minutes
WASHINGTON — Astronomers have detected an act of extreme violence across more than half the known universe as a black hole shreds a star that got too close to this celestial savage. But this was no ordinary example of a starved black hole.
It was one of just four examples — and the first since 2011 — of a black hole seen ripping apart a passing star in a so-called tidal disruption event, then launching glowing jets of high-energy particles in opposite directions from space, researchers said. And it was both the most distant and the brightest such event on record.
Astronomers described the event in studies published Wednesday in the journals Nature and Nature Astronomy.
The culprit appears to be a supermassive black hole thought to be hundreds of millions of times the mass of our sun and located about 8.5 billion light-years from Earth. A light year is the distance that light travels in one year, 5.9 trillion miles.
“We think the star was similar to our sun, maybe more massive, but of a common type,” said astronomer Igor Andreoni of the University of Maryland and NASA’s Goddard Space Flight Center, lead author of one of the studies.
The event was discovered in February by the Zwicky Transient Facility astronomical survey using a camera attached to a telescope at the Palomar Observatory in California. The distance was calculated with the Very Large Telescope of the European Southern Observatory in Chile.
“When a star comes dangerously close to a black hole – don’t worry, that won’t happen to the Sun – it will be violently torn apart by the black hole’s tidal forces – similar to how the Moon pulls tides on Earth, but with greater force,” he said he Michael Coughlin, astronomer and co-author of the study from the University of Minnesota.
“Then parts of the star are captured in a rapidly spinning disk that orbits the black hole. Eventually, the black hole will consume the remains of the doomed star in the disk. In some very rare cases, which we have estimated to be 100 times rarer, powerful jets of material are ejected in opposite directions when the tidal disturbance event occurs,” Coughlin added.
Andreoni and Coughlin said the black hole is likely spinning rapidly, which could explain how the two powerful jets were ejected into space at almost the speed of light.
Massachusetts Institute of Technology astronomer Dheeraj Pasham, lead author of the other study, said researchers were able to observe the event very early — within a week after the black hole began consuming the doomed star.
While researchers note tidal disturbances about twice a month, those that produce jets are extremely rare. One of the jets emanating from this black hole appears to be pointing toward Earth, making it appear brighter than it would if it were flying in a different direction – an effect called “Doppler boosting,” which resembles the amplified sound of a passing police siren .
The supermassive black hole is thought to be at the center of a galaxy – just like the Milky Way and most galaxies have one at their core. But the tidal disturbance event was so bright that it eclipsed the light of the galaxy’s stars.
“At its peak, the source appeared brighter than 1,000 trillion suns,” Pasham said.