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Why don’t planet hunters find black holes?

  1. Mar 21, 2008 #1


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    Over 200 planets have been discovered by the radial velocity technique. Why no black holes? For similar periods, the signal amplitude should be much greater.
    TIA. Best,
    Jim Graber
  2. jcsd
  3. Mar 21, 2008 #2
    I'm no expert in this area, but I believe that such systems (a star orbiting a black hole) would inevitably become what are known as "X-ray binaries", as matter is drawn from the star into a hot X-ray-emitting accretion disc around the black hole. The stellar spectral lines in such systems are indeed subject to enormous periodic Doppler shifts. I'm not sure how X-ray binaries are normally discovered though...
  4. Mar 21, 2008 #3
    BHs are not nearly as common as planets
    while they would really bounce a star's orbit
    just looking for X-rays is a more common way to find them

    V4641 Sgr is 1600 light years away at the closest found
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