Tour: Black Hole Destroys Star and Goes After Another

A massive black hole has torn apart one star and is now using that stellar wreckage to pummel another star or smaller black hole that used to be in the clear. This discovery, made with NASA’s Chandra X-ray Observatory and other telescopes, helps astronomers link two mysteries where there had previously only been hints of a connection.

In 2019, astronomers witnessed the signal of a star that got too close to a black hole and was destroyed by the black hole’s gravitational forces. Once shredded, the star’s remains began circling the black hole in a disk in a type of stellar graveyard.

Over a few years, however, this disk has expanded outward and is now directly in the path of a star, or possibly a stellar-mass black hole, orbiting the massive black hole at a previously safe distance. The orbiting star is now repeatedly crashing through the debris disk, about once every 48 hours, as it circles. When it does, the collision causes bursts of X-rays that astronomers captured with Chandra.

Like a diver repeatedly going into a pool and creating a splash every time she enters the water, the star striking the disk creates a huge ‘splash’ of gas and X-rays. As the star orbits around the black hole, it does this over and over again.

Scientists have documented many cases where an object gets too close to a black hole and gets torn apart in a single burst of light. Astronomers call these “tidal disruption events,” or TDEs. In recent years, astronomers have also discovered a new class of bright flashes from the centers of galaxies, which are detected only in X-rays and repeat many times. These events are also connected to supermassive black holes, but astronomers could not explain what caused the semi-regular bursts of X-rays. They dubbed these “quasi-periodic eruptions,” or QPEs.

This discovery gives astronomers evidence that TDEs and QPEs can be different phases of the same phenomenon. In addition to Chandra, the researchers used NASA’s Hubble Space Telescope, NICER telescope aboard the International Space Station, and the Neil Gehrels Swift Telescope. Astronomers will continue to look for more of these events to learn more about how black holes grow, and to study the prevalence and distances of objects in close orbits around massive black holes.