Chapter 17 Quasars and Active Galaxies term accretion

Chapter 17 Quasars and Active Galaxies

term: accretion disk [ click for answer ] 1 of 7

definition: Matter that an object has taken up and that has formed a disk around the object. [ click for next term ] 1 of 7

term: active galactic nucleus (AGN) [ click for answer ] 2 of 7

definition: A galaxy nucleus that is exceptionally bright in some part of the spectrum; includes radio galaxies, Seyfert galaxies, quasars, and QSOs. [ click for next term ] 2 of 7

term: active galaxy [ click for answer ] 3 of 7

definition: A galaxy whose nucleus radiates much more than average in some part of the spectrum, revealing high-energy processes; radio galaxies and Seyfert galaxies are examples. [ click for next term ] 3 of 7

term: gravitational lensing [ click for answer ] 4 of 7

definition: In the gravitational lens phenomenon, a massive body changes the path of electromagnetic radiation passing near it so as to make more than one image (or a brightening) of an object. A double quasar was the first example to be discovered. [ click for next term ] 4 of 7

term: quasar [ click for answer ] 5 of 7

definition: A very-large-redshift object that is almost stellar (point-like) in appearance, but has a very nonstellar spectrum consisting of broad emission lines; thought to be the nucleus of a galaxy with an accreting supermassive black hole. [ click for next term ] 5 of 7

term: superluminal speed [ click for answer ] 6 of 7

definition: An apparent speed greater than that of light. [ click for next term ] 6 of 7

term: supermassive black hole [ click for answer ] 7 of 7

definition: A black hole of millions or billions of times the Sun's mass, as is found in the centers of galaxies and quasars. [ End of chapter 17] 7 of 7