Question 1:

This exercise is the same as the Interactive exercise #2 that is located in Module 2 Lecture D.

• Launch the Periodic Table

• Launch the Absorption Line Simulator).

  Set the temperature to 10,000 degrees.

  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. 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)

  Enter the four wavelengths for AX and BX into the worksheet into the appropriate column in the worksheet as well as your choice for elements, from the Periodic Table, that best correspond to AX and BX.

  
  
  
  
  
  
  
  
  

  Question 2:

  Refer to the right diagram and answer this series of questions:

  a) List all the possible values of photon energies that this atom "emit" if the electron is moved to the highest energy level shown in this diagram (e.g. energy level = 12)
  
  
  

  b) If an incoming photon has energy = 9 units and the electron is in the ground state (as pictured), what will happen to the incoming photon and the electron?

  
  
  c) if the electron is in the first excited state (e.g. energy level =5) and in incoming photon of of energy = 5 units hits the atom, what will happen to that photon and the electron?

  
  
  
  
  
  
  
  
  
  Question 3. This refers to the material in Module 3 Lecture A as related to the determination of stellar parallax by Tycho.

  Open the simulation.

  At the bottom is your detector, in this case 3 independent pixels. The eye above reflects the orbit of the Earth around the Sun. The angle is the parallax angle. In order for a parallax to be detect, the Star has to move at least one independent pixel. In this default case, there is no detection (the star is too far away and/or the resolution of the detector is too imprecise).

  The course grid simulates measurements from the ground through our atmosphere.

  The Fine Grid refers to measurements made from space.

  Separation refers to distance from the Earth to the star; smaller values are larger distances.

  a) With the course grid checked (i.e. 3 pixels), what is the required minimum separation (i.e. the distance to the star) to produce a detection. Increment the seperation by clicking on the arrows?

  b) Leaving the separation at that minimum value, click on Fine Grid. How many pixels (e.g. resolution elements) of movement is there in this case?

  c) With the fine grid, explain whether or not you can detect stellar parallax at the largest seperation (e.g. seperation = 1).

  d) Now explain why space based observations offer a much better way of detecting stellar parallax than can be done from the ground.

  Question 4

  This question will make use of the simulator first encountered in module 1 Lecture E: Interactive Exercise - so you might want to practice with that. You will be working with two Stars below.

  Star 1 (right click to open in new window)

  • Click on Point (otherwise nothing works)
  • Make your first measurement near the edge of the visible star as shown below and make 5-6 additional measurements at other places around the star as shown below:
    

  • You can click on any of the green points to measure there X (distance) and Y (flux values).

    a) Record in the worksheet the flux of this star at distance = 12 Units

    b) Now click points in the black at larger distances from the star and determine the limiting distance to this star (that is at what distance does the flux decline to zero?)

  Star 2 (remember to select point, else it doesn't work)

  c) determine the limiting distance for Star 2

  d) What is the approximate brightness ratio between Star 1 and Star 2 - you have enough information to determine this so explain your determination of this reatio.