Aasign14.htmClick here to go back to Astronomy Assignments

Name______________________________

Materials: 1 set or dark line spectra cards per pair

Read this first:

Dark line spectra are caused by elements in the atmosphere of the star absorbing the light coming from the star at that particular wave length. It is a bit like looking at a negative of a photograph. We can look at the dark lines in a stars spectra and determine its temperature, composition and velocity.(speed with direction)

PROCEDURE:

• Line the strips so that the key number is on the left
• Change the strips around so that they are in some kind of order . You may use any arragnement that you like as long as it has a particular meaning.

1. Why did you arrange them in the way you did?_____________________________________

• Now arrange the strips by composition-i.e. by the pattern and sizes of the lines which its chemical elements form. Write the letters of the strips in order from the most lines to least lines:

2. MOST LINES_____ ______ ______ ______ ______ ______ ______LEAST LINES

3.Which stars seem the LEAST alike in composition? _________ and ___________

• Now arrange the stars according to temperature-(The more dark lines the lower the temperature)
• Write the letters from the hottest to the coolest star

4. HOTTEST_______ ______ ______ ______ ______ ______ ______ COOLEST

5. Which star contains the most elements?________________________________________

6. Which is the coldest star?____________________________________________________

7. The strip with the least dark lines is the hottest. About how many different elements are represented in this strip?_______________________________

8. Draw the hottest star's dark line spectra here:

9. What causes the dark lines in a dark line spectrum?(see above)