QUASARS (Quasi-Stellar Radio Source) [QSR]
- Appear like stars
- Emits strong radio signal
- Distant active nuclei of galaxies
- A compact region in the center of a massive galaxy surrounding its central supermassive black hole
- Traveling away from Earth at tremendous speeds (largest Doppler red shifts known)
- First discovered 20 years ago (3C273) by interaction of optical and radio astronomy
- In 1963, Maarteen Schmid discovered a quasar with a 16% Doppler red shift (~3 billion light years away)
- Since then, more than 1,500 quasars discovered with red shifts up to 473%
- Provide information of the early phases of the Universe
- Have been found in a cluster of galaxies (“host galaxies”)
Hubble’s Law: large redshift means large velocities of recession = great distances