This pair of visible-light and near-infrared photos from NASA's Hubble Space Telescope shows the giant star N6946-BH1 before and after it vanished out of sight by imploding to form a black hole. The left image shows the star, which is 25 times the mass of our sun, as it looked in 2007. In 2009, the star shot up in brightness to become over 1 million times more luminous than our sun for several months. But then it seemed to vanish, as seen in the right panel image from 2015. A small amount of infrared light has been detected from where the star used to be. This radiation probably comes from debris falling onto a black hole. The black hole is located 22 million light-years away in the spiral galaxy NGC 6946. https://photojournal.jpl.nasa.gov/catalog/PIA21467

Every second a star somewhere out in the universe explodes as a supernova. But some extremely massive stars go out with a whimper instead of a bang. When they do, they can collapse under the crushing tug of gravity and vanish out of sight, only to leave behind a black hole. The doomed star N6946-BH1 was 25 times as massive as our sun. It began to brighten weakly in 2009. But, by 2015, it appeared to have winked out of existence. By a careful process of elimination, based on observations by the Large Binocular Telescope and NASA's Hubble and Spitzer space telescopes, researchers eventually concluded that the star must have become a black hole. This may be the fate for extremely massive stars in the universe. This illustration shows the final stages in the life of a supermassive star that fails to explode as a supernova, but instead implodes to form a black hole. https://photojournal.jpl.nasa.gov/catalog/PIA21466