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Fraser
2006-Nov-29, 01:53 AM
Astronomers have discovered a gamma ray source in the sky that acts like a natural clock. The object is called LS 5039, and consists of a massive blue star orbiting an unknown object - possibly a black hole. The two objects orbit each other closely, completing an orbit every four days. With each orbit, the black hole flies through the blue star's stellar wind, and accelerates particles to gamma ray levels. This is the first time a source of gamma rays has been discovered with such a regular schedule.

Read the full blog entry (http://www.universetoday.com/2006/11/28/set-your-clock-with-gamma-rays/)

ioresult
2006-Nov-29, 05:01 PM
quote: "Symmetrically, when very energetic gamma rays meet the light from a massive star, they can be converted into matter (an electron-positron pair in this case)."

what? a gamma photon and a visible light photon can collide and create a pair of particle-antiparticle?

I didn't know photons could collide!

wstrnmdw
2006-Dec-04, 05:03 PM
For a short description, see section 4.1 in the following PDF, which is the original report:
http://www.aanda.org/images/stories/PressRelease/PRaa200616/praa200616.pdf

Wesley

C18H27NO3
2006-Dec-05, 07:27 PM
For a short description, see section 4.1 in the following PDF, which is the original report:
http://www.aanda.org/images/stories/PressRelease/PRaa200616/praa200616.pdf

Wesley

From section 4.1

"VHEγ-rays produced close enough to the stellar companion will unavoidably suffer severe absorption via pair production
(e+e−) on its intense optical photon field."

I also didn't know photons could collide so I looked up section 4.1. After reading it several times, :doh: I caught the basic idea.

Thanks, Wesley.