February 1, 2011 Issue

Physics To Go 110 - Quasars

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Physics in Your World

3C273 - Quasar in Virgo image
image credit: Wikimedia Commons; image source; larger image

3C273 - Quasar in Virgo

In a telescope, object 3C273 will look like an ordinary star to you--it looked like an ordinary star to astronomers until the 1950s, too. In fact it is a quasar, or quasi-stellar radio source. These objects might look like stars, but they emit radio noise and are very distant--in the case of 3C273 above, nearly 2.5 billion light years away.

3C273 is bright enough to be seen with a very good backyard telescope. If you can find it, you can look back billions of years in time. Read 3C273 - Quasar in Virgo to learn how to find it in the night sky.

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Physics at Home

Balloon Analogy in Cosmology

Quasars are the most distant objects we can see from Earth. Their light reaches us from billions of years in the past. Astronomers know how far they really are from us because the light we see is dramatically redshifted, meaning they are moving away from us astonishingly fast. See the Balloon Analogy in Cosmology to learn more about the expansion of the universe and how astronomers use redshift to measure distances in space. Find out how you can paste galaxies on a balloon and make a model of how the universe expands.


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From Physics Research

Chandra Observes Cosmic Traffic Pile-Up In Energetic Quasar Jet image
image credit : NASA/CXC/SAO/H.Marshall et al.; image source; larger image

Chandra Observes Cosmic Traffic Pile-Up In Energetic Quasar Jet

This X-ray image of 3C273 shows a jet of energy shooting out of the quasar's bright center, thought to be home to a supermassive black hole. If you look closely you can see a small thread connecting the center to the bright spots of the jet. Scientists have observed that matter from that small thread moves very fast, then appears to slow down in the luminous part of the jet, akin to a "cosmic traffic pile-up" of matter. For more details, see Chandra Observes Cosmic Traffic Pile-Up In Energetic Quasar Jet.


Worth a Look

3C273 Activity: Faster Than a Speeding Bullet...

How fast is that jet in the image above moving away from the quasar? You can calculate the velocity yourself in 3C273 Activity: Faster Than a Speeding Bullet... from Chandra. You'll find that it's moving impossibly fast--faster than the speed of light. The activity explains how this appears to be true. If you want to learn more about the calculations astronomers use for large distances, be sure to check out the other activities on 3C273, too.


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