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posted by  Sherron on 7/24/2008 9:23:33 AM  |  status: Live  

The Physical Universe Q9 / T6 (lifesaver)

Course Textbook Chapter Problem
N/A The Physical Universe Konrad B. Krauskopf Arthur Beiser T6 9
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9. How do we know that stars are made mainly of hydrogen?

A. Material sampling by satellites

B. Spectrum analysis

C. Detection of neutrinos

D. Emission of protons from the sun
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posted by AnswerDesk on 7/24/2008 10:08:13 AM  |  status: Live
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Answer:  B

Spectrum analysis (or spectrometry) can be used to determine chemical composition of stars by examining the emission and absorption spectral lines.  Spectral lines are atom/molecule specific, so patterns from an observation can be compared to known, locally observed samples.  In particular, the spectral lines for hydrogen have been rigorously studied.  Read about spectroscopy and spectrometry for more information.

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posted by eljose on 7/24/2008 10:09:45 AM  |  status: Live
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b. we know this by spectrum analysis, they use what is called Astronomical spectroscopy
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posted by Sarah21 on 7/24/2008 10:10:11 AM  |  status: Live
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B) Spectrum analysis
 
Each element has its own spectra when we analyze the emitted light.
 
Scientist analyze the light from a star using a device called a spectrometer. Light from the elements passing thru the spectrometer make a certain pattern for that element. All the elements involved will combine together to make one big graph but it is easy to separate the patterns to determine which elements the light contains. therefore the star will be made of those elements.
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