Any physical object smaller than its Schwarzchild radius will undergo gravitational collapse to become one, and they might lose mass by slowly emitting Hawking radiation.
Types include the Kerr-Newman and Reissner-Nordström varieties, a classification based on two of the independent internal properties described by the "no hair" theorem. In the theorized Penrose process, one can extract energy from rotating ones, which have two photon spheres, an ergosphere, and an accretion disk. Any physical object smaller than its Schwarzchild radius will undergo gravitational collapse to become one, and they might lose mass by slowly emitting Hawking radiation. FTP, name these astronomical entities that possess an event horizon.
Types include the Kerr-Newman and Reissner-Nordström varieties, a classification based on two of the independent internal properties described by the "no hair" theorem.
{black holes}