Hubble_Redshift_Lab_01-12-10

Hubble_Redshift_Lab_01-12-10 - Expansion of the Universe1...

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Expansion of the Universe 1 Purpose: To measure the Doppler shift of absorption lines in the spectra of galaxies in order to caculate their radial velocity and plot a Hubble diagram of velocity vs. distance. The slope of the graph will be used to determine the Hubble Parameter and from that an estimate of the age of the universe. In addition students will use real data collected in the Galaxies and Citizen Science lab to see if these galaxies fit the pattern. Part I Telescope: The Expansion of the Universe lab simulates the operation of a computer-controlled spectroscope attached to the research telescope at Gettysburg College Observatory. Open the Hubble Redshift. You can use this spectroscope to look at the spectrum for a galaxy in the same way you used a simulated spectrometer to look at the spectra for various stars earlier in the course. As before open the dome and turn on tracking. You will see a view of the sky with several “blobs” that are actually galaxies full of stars. You can use the N,S,E and W buttons to move through this field of stars and galaxies, or choose another field of view by clicking FIELD. Each field of view is at approximately the same location and distance from earth. Once the telescope is operational you can do the following: Select a Field of View (there are 6 to choose from) Select an Object to Study Use the spectrometer to collect a spectrum for the galaxy Analyze the Spectrum Spectrometer: As you move through any of the fields you will see galaxies, but also other bright objects. It will take a little practice to identify the galaxies in a field. Since galaxies are mostly collections of stars, the spectrum of a normal galaxy is a kind of “averge” of the spectra of its stars. You should see a spectrum for the galaxies in this experiment that have the H and K absorption lines for calcium both broadened and shifted. Nearby stars are too close to show Doppler shifts, and will also have
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Hubble_Redshift_Lab_01-12-10 - Expansion of the Universe1...

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