Review Questions for Exam #2
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Review Questions for Exam #2
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In order to figure out the mass of a star we observe binary star systems and use Kepler’s 3rd
Law, (M1 + M2) P2 = 4π2*a3/G
Discuss how we determine, P and a.How do we solve for individual mass (like M1)
rather than (M1 + M2)?
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• Sketch an H-R diagram. Label the axes and indicate the direction of increase along each axis.
• Draw in the location of the main-sequence, super giants (I) the giants (III) and the white dwarfs.
• On the main-sequence, indicate with an arrow the direction of increasing mass.
• Given the arrow that you have drawn, how are luminosity and mass related on the MS and why?
• Put a big “R” in the place where on the diagram where the radii are the biggest. Put a “r” where the radii are the smallest.
• Given the relation L = σT4(4πR2) explain why the “R” and “r” are at the locations you have labeled
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• Here is an image near the center of the Orion nebula, a star forming region.
• Explain what is happening in this picture• Explain how this is related to the process of
self-sustained star formation in the molecular cloud.
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Fe
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• Discuss how the absorption lines form. What has to be true about the electrons in order to create absorption lines?
• What do the strength of the absorption lines depend on?
• In the spectra below, the temperature is the same for all three spectra. Why are the lines different strengths?
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Explain what is happening to the proto-star as it follows the track below.
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Explain this diagram
• What is going on at #1, #2, #3, #4?• In #3 what is happening on the outside of the star?
Why?
#1
#2
#3#4
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• Explain why a high mass core cannot get energy out of fusion of Iron.
• What happens to the core of a high mass star when it becomes iron?
• How does it produce a supernova?
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• Explain why a neutron star spins incredibly fast.
• How do we know that neutron stars really do spin rapidly?
• What objects show us that neutron stars spin fast?
• How does this object work?