AST-1002 Chapter Notes - Chapter 17: Accretion Disk, Electromagnetic Spectrum, Radio Galaxy
Document Summary
Because of their starlike appearances and strong radio emissions, 3c 48 and 3c 273 were dubbed quasi-stellar radio sources, a term soon shortened to quasars. Related objects, called quasi-stellar objects (qsos), also look like stars but have strong energy outputs in all different parts of the electromagnetic spectrum, with most being strongest in the infrared. More than 200,000 quasars and qsos have been discovered. In this book, we will use the word quasars to cover qsos, too. Quasar (quasi-stellar radio source) - a starlike object with a very large redshift. A typical large galaxy, like our own milky way, contains hundreds of billions of stars and shines with the luminosity of 10 billion suns. The largest and most luminous galaxies, the giant ellipticals, are only 10 times brighter. Beyond 8 bly from earth, even the brightest galaxies are too faint to be easily detected. Most ordinary galaxies are too dim to be detected at half that distance.
