Place the items based on whether or not they are real methods used for detecting black holes. Category Method for detecting black holes Category Not a method for detecting black holes, sudden disapperance of a star orbiting a black hole, direct observations of hawking radiation, empty areas in space where a black hole swallowed all nearby stars, x-ray observations of an accretion disk, gravitational of an accretion disk, gravitational effects on objects orbiting black holes, looking for the trail of destruction left by a passing black hole, motion of a binary companion