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Planetarium Activity

Turn off the daylight display. Using the “Selection” button, select “Find”. Type in the name “Ursa Major” and click on Find. Go to “Guides” then Constellations and select Astronomical. This should show you the boundaries of Ursa Major and the outline of the constellation. Using the Selection Tool, click on one of the stars in Ursa Major. Open the “Display” Palette on the vertical toolbar and click on the Const button. One by one, use the Selection Tool to point at the stars that outline Ursa Major (there are 20 of them), and right click with the mouse. Then click on Info Window. Record the name of the star, its temperature, and B-V Colour Index. (For Alkaid, the star at the end of the handle of Ursa Major, the temperature and B-V Colour Index are 11,235 and 0.10.) B-V Colour Index is the difference between the magnitudes of the star in the middle of the visual part of the spectrum and the blue part of the spectrum. Arrange the stars according to temperature from hottest to coolest. How is B-V related to temperature? Explain the relationship between B-V and stellar temperature.

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