Figure: A Hubble Space Telescope image of a quasar reveals the
presence of a galaxy surrounding the quasar's bright nucleus.
From quasi-stellar object, a star-like (i.e. unresolved) object that has a very large luminosity and is located at very large distances from us (as indicated by their high cosmological redshifts). Although technically the term quasar refers to objects that are highly luminous in the radio band, the term tends to be used for both radio-loud and radio-quiet objects high-redshift unresolved objects. Quasars are believed to be powered by supermassive black holes in the centers of galaxies in the process of formation early in the history of the universe.
Figure: A Hubble Space Telescope image of a quasar reveals the
presence of a galaxy surrounding the quasar's bright nucleus.