Black Hole
A black hole is an astronomical object whose gravity is so strong that nothing—even light—can escape from within its event horizon. It forms when a massive star’s core collapses or through other processes, and may have an accretion disk of infalling matter that emits radiation. Supermassive black holes at galaxy centers influence stellar orbits, and mergers produce gravitational waves.
Source: nasa.gov
APODs including "Black Hole"
Micro-Quasar GRS1915 Puffs
02/12/1997
On the far side of our Galaxy, gas clouds explode away from a small black hole. This might seem peculiar, as black holes are supposed to attract matter. But material falling toward a black hole collides and heats up, creating an environment similar to a quasar that is far from stable. In the above time-lapse sequence, micro-quasar GRS1915 expels bubbles of hot gas in spectacular jets. These computer enhanced radio images show one plasma bubble coming almost directly toward us at 90 percent the speed of light, and another moving away. Each of the four frames marks the passage of one day. Originally detected on October 29th, these bubbles have now faded from view.