Lab 4

Background

The discovery of planets outside the solar system was a major turning point in the history of astronomy because it revealed that not all systems resemble the system we live in. In this lab, you'll look at data on some known extrasolar planets using publicly-available data to draw conclusions about the nature of extrasolar planets.

Directions

This lab exercise consists of only one "part," and all of the exercises are given below. Please record your answers to ALL of the items below in a single document.

1. There are eight planets in the Solar System. Some data on these planets is provided below. For each planet, calculate its density relative to the Earth's density:

   Planet Data

   Planet	Distance from the Sun (in AU)	Mass (Earth Masses)	Radius (Earth Radii)
   Mercury	0.387	0.06	0.382
   Venus	0.72	0.82	0.949
   Earth	1.00	1.00	1.00
   Mars	1.52	0.11	0.53
   Jupiter	5.20	318	11.2
   Saturn	9.54	95	9.41
   Uranus	19.22	14.6	3.98
   Neptune	30.06	17.2	3.81

2. There are two types of planets in the solar system, terrestrial planets (like the Earth) and gas giants (like Jupiter). How do the mass, radius, and densities of these planetary types differ?
3. Let's say you discover a planet that's 50 times the mass of the Earth. Even without visiting the planet, what might you presume about the planet?
4. How do the distances from the Sun differ for terrestrial and Jovian planets?
5. Go to the http://exoplanets.org/ website. (We will discuss extrasolar planets in more detail in Lesson 12.)
6. Scan the page. How many planets have been discovered to date?
7. Click on the "Plots" button.
8. Click on the Histogram Plot button near the top right, and it will show you histograms of the properties of the candidates (for example, the numbers of objects in given ranges of mass). Select various properties to plot and observe the results. If the histogram looks odd and doesn't seem to show more than one bar, choosing the "Logarithmic bins" option should improve the plot.
9. Click on the "Add Filter" button in the "Configure Histogram" area on the page. Click on the plus sign on the right side of the Filter box, and it will bring up a menu. Choose "Table Filter RV Planets" to select only those planets discovered using the radial velocity method.
10. Answer the following questions:
    • Are most of the planets found using this method more massive or less massive than Jupiter? Note that the unit "M_J" means "Jupiter masses".
    • Do most of these planets have orbital periods that are shorter or longer than a year? (Note, you should select "logarithmic bins" for this one)
    • Are most of the planets closer to or farther from their stars than the Earth is to the Sun?
11. Click on the "Scatter Plot" button. Here you can look at the relationship between different planetary and stellar parameters.
12. Create and inspect a plot with an x-axis of "Planet Semi-Major Axis" and a y-axis of "Planet Mass". Do you notice any patterns or clumps? If so, describe them.
13. Using the data in the table above, eyeball where Jupiter, Saturn, Uranus, and Neptune would lie on your plot. Do any of the Jovian planets in our Solar System lie in any of the clumps on the plot? Describe their location.
14. Write a summary that includes a short comparison between the properties of the planets in our Solar System that you studied above to the properties of the extrasolar planets you studied here.
15. Save your work (that is, all of your answers and your summary) AS A SINGLE DOCUMENT in either a Microsoft Word or PDF file in the following format:
    
    Lab4_AccessAccountID_LastName.doc (or .pdf)

    For example, student Elvis Aaron Presley's file would be named "Lab4 _eap1_presley.doc" - This naming convention is important, as it will help me make sure I match each submission up with the right student!