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I By what formula is this graph predicted? Cumulative Periastron Time Shift

  1. Oct 30, 2016 #1
    B1913+16.gif
    I'm confused about how the predictions of this graph were formed.
    I have this formula:
    Untitled.png
    But the change in frequency per second is about : 2x 10^-12 which has a problem because when you multiply this by 10 years you don't even get a change of frequency of 1/1000 of a second and in the graph it says it's around 5 seconds.
    Anyone know what I'm doing wrong?

    Paper: https://arxiv.org/pdf/1011.0718v1.pdf
     
  2. jcsd
  3. Oct 30, 2016 #2

    mfb

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    2016 Award

    Staff: Mentor

    This is the cumulative change in time, not in frequency. You need the integral or sum.

    The first measured orbit was about 7.75 hours, the next was 2.4 * 10-12 * 7.75h = 67ns shorter (integrated shift: 67 ns), the following one was 2*67 ns shorter than the first one (cumulative shift: 67+2*67 = 201 ns) and so on.

    In 10 years, there were 11300 orbits, for a cumulative shift of 1/2 * 67 ns * 113002 = 4.3 seconds, in agreement with the parabola shown there.
     
  4. Oct 30, 2016 #3
    Thx so much this was the answer I was looking for !!!
     
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