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Homework Help: Astronomy Help with Spectrography

  1. Dec 4, 2006 #1


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    1. The problem statement, all variables and given/known data
    I posted a similar question before but I am just having some difficulty understanding the relevance of one of things mentioned in this question and I'm wondering if anyone here can help clarify it. The problem is what is the relevance of the star spinning at a velocity of 6000 km/s. This is the question:

    2. An observer is observing a STAR A that has a shell of Hydrogen around it. The shell is uniform in terms of the density distribution. Let’s assume that the shell is collapsing at the uniform velocity of 10000 km/s. In addition to the collapsing motion, STAR A is also spinning at the velocity of 6000 km/s. If the surface temperature of STAR A is 5000 K and the shell only emits (or absorbs) n = 7 – 4 transition of Hydrogen, what does the observed spectrum look like at the 0.1 – 3.0 micron range. Specify all possible line transitions as well as a sketch of continuum to the scale. The relative strength of the line emission to the continuum emission is 0.5 at the maximum.

    2. Relevant equations

    3. The attempt at a solution
    What I am thinking is that since the star is spinning it will cause a red shift on one side and a blue shift on the other side and the result will be a continuum with a slightly stretched peak.

    However my problem with this is that it really does not contribute much to my final answer and it will just result in me drawing a graph with a slightly different looking peak. And since we have already done a similar question to this in a previous assignment I think that he would add something more significant.

    So if anyone can think of a more logical reason for him to add this in then please help me out here, thanks!
  2. jcsd
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