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Quasar Host Galaxies
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Hubble Space Telescope image courtesy of STScI

Quasi Stellar Objects: Quasars and Active Galaxies

Quasars, or quasi stellar objects, are named that way because they are star-like in appearance. But they are nothing like stars. They are very distant, some are the most distant objects that we can see. They are also very bright. What could they be? For many years Astronomers did not know.

Astronomers now think that Quasars are the centers of Active Galaxies. In the center of many galaxies there may rest supermassive Black Holes. Around these Black Holes gigantic discs of material fall on them. This material is heated to incredibly high temperatures and that makes them very bright. Some Quasars outshine their host galaxies.

The Black Holes also form jets of matter that shoot out from the center of the galaxy. When the galaxy is aligned so that we look straight down the jet we see a Quasar.

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