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Thread: Set Your Clock with Gamma Rays

  1. #1
    Join Date
    Jul 2003
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    29,015

    Post Set Your Clock with Gamma Rays

    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

  2. #2
    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!

  3. #3
    Join Date
    Aug 2005
    Posts
    2

    Post They Do

    For a short description, see section 4.1 in the following PDF, which is the original report:
    http://www.aanda.org/images/stories/...praa200616.pdf

    Wesley

  4. #4
    Join Date
    Nov 2006
    Posts
    186
    Quote Originally Posted by wstrnmdw View Post
    For a short description, see section 4.1 in the following PDF, which is the original report:
    http://www.aanda.org/images/stories/...praa200616.pdf

    Wesley
    From section 4.1
    "VHE
    γ-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, I caught the basic idea.

    Thanks, Wesley.


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