It didn't actually "eat a star." A star passed close enough to it that the tidal forces ripped the star apart and the star became a ring (accretion disk) around

It didn't actually "eat a star." A star passed close enough to it that the tidal forces ripped the star apart and the star became a ring (accretion disk) around the black hole. Matter in an accretion disk gets very hot because of gravitational acceleration and friction -- so hot it can shine more brightly than the original star. And what probably really happened is that the star was massive enough that it caused the black hole to start emitting jets. There are always two of these pointed opposite one another, and one happened to be pointed toward us. https://en.wikipedia.org/wiki/Astrophysical_jet https://en.wikipedia.org/wiki/Astrophysical_jet