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Homework Help: Question concerning Michelson stellar interferometer

  1. Nov 15, 2008 #1
    Hello there, I have a question concerning Michelson stellar interferometer.
    It is about stars ejecting mass in a thin luminous shell of gas expanding to a size greater than that of star itself.
    So it says in the exercise:
    a michelson interferometer is used as a fourrier transform spectrometer to examine radiation from an area of sky neart he star so as to include contributions from the front and back of the shell but not from the star itself. the visibility curve obtained for a spectral line of wavelength 656 nm is given( sketch of sinc function).
    How can I estimate the velocity of expansion of the shell and the apparent width of the component lines?

    Thank you
  2. jcsd
  3. Nov 16, 2008 #2

    Andy Resnick

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    Re: Coherence

    This is a good question. As a hint, Michaelson interferometers measure *temporal* coherence, not *spatial* coherence. So, what is the visibility curve actually measuring?
  4. Nov 16, 2008 #3
    Re: Coherence

    I suppose that it has to do with the temporal coherence of the source so this would mean that what we see in the graph is the change in visibility at different times during its expansion?
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