Glossary -- Q

quasar

short for ``quasi-stellar radio source''. Quasars are the most luminous of active galaxies---they are the extremely active nuclei of otherwise normal galaxies. Quasars generate a huge amount of energy within very tiny volumes. Because they are most luminous things known, quasars can be seen at very large distances. Looking like blue stars, they can be distinguished from stars by the presence of broad emission lines instead of the narrow absorption lines of normal stars, their large redshifts because of their very large distances (see the Hubble Law), and many quasars are strong radio sources, unlike stars which have weak radio emission.

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last updated: 27 May 2001