1. Do Interactive exercise #2 that is located in Module 2 Lecture D. (Link is on left top of lecture D) This exercise refers to identifying elements AX and BX. Ignore the 'Measurements' table that pops up. It's a relic of an in class demo. Instead just type your answers in your homework that you'll email to me. I suggest trying interactive exercise #1 to get a feel for the widget. PLEASE READ ALL THE INSTRUCTIONS ON THE INTERACTIVE EXERCISE PAGE FIRST BEFORE STARTING IT -it will make more sense this way. You will also need to open the periodic table widget (located on the same page) as well. To the right is an example screen shot for element AX showing the 4 spectral lines (wavelengths omitted) that you would need to match up with the periodic table of elements. The white line at the top labelled 4105/0 is what you slide up up and down to measure the wavelengths of the 4 dark lines. Please note that the number of lines shown in this widget isn't the total number of absorption lines for the elements you are to determine. It is, however showing you the stronger absorption lines. Your response to this question should include
   • the wavelengths of the identified lines in AX and BX.
   • Which element in the periodic table that you think corresponds to AX and BX (remember, AX and BX both are elements with atomic numbers less than 20)

   
   
   
   
   
   
   
   

   For the next question you will need to look up some facts (ie. google them) online. Answers just have to be a few sentences.

2. Astronomers have recently discovered a new spectral type for stars. They are classified as Spectral type L. When were these stars first discovered, how were they discovered and what kind of stars do they appear to be?
   
   

   These 4 questions are designed to test your knowledge of applying the inverse square law. All units are in relative units.

   The following shows the properties of 5 stars. Luminosity refers to the intrinsic energy output of the star and all luminosity values refer to the luminosity of Star A which is 1 luminosity Unit.

   Star A is at a distance of 10 distance units and deposits a flux of 100 flux units on our detector.

   Believe it or not, this is all the information needed to answer the questions. All of the units are relative to Star A so you simply scale from what you know for Star A to determine either the flux, luminosity or distance of the other Stars.

   • Star A: Luminosity = 1 luminosity unit Distance = 10 distance units Flux = 100 flux units
   • Star B: Luminosity = 1 luminosity unit Distance = 100 distance units
   • Star C: Luminosity = 4 luminosity units Distance = 40 distance units
   • Star D: Flux = 200 flux units Distance = 10 distance units
   • Star E: Luminosity = 1 luminosity unit Flux = 25 flux units

   Show all work or reasoning in answering the following questions.

3. What is the number flux units on the detector for Star B?

4. What is the number of flux units on the detector for Star C?

5. What is the number of luminosity units of star D?

6. What is the distance of Star E?