Goals for Dark Matter Lab
I could write out a long list of the goals for this lab, some that I came up with beforehand, but many that explain the difficulties I saw kids having with the material. I started writing that list, but it looked long, complicated, and confusing. So, I've broken the goals up between questions. I wrote the questions with the intention at getting at particular goals, so here's how it works out. For the most part, the answers to the questions are the goals. I am not saying that the goals are only addressed in each particular question. No, the goals relate to the entire lab, we are just focusing on particular things in each question. The questions should help guide the students to the various pieces of understanding that we expect them to get.
- Get kids to say, "Wow, there's a lot of matter that we can't explain."
- This is a spiral galaxy, you can see the ordered rotation.
- This is a GALAXY, that means it's big and is made of lots of stars.
- Practice plotting (deciding on axes)
- Mass on vertical, radius on horizontal
- LABLE AXES!!!
- plotting over 3 decades (108->1010)
- How do we deal with the scientific notation? Should be OK on linear plot
- Brings home the fact that 109 = .1 * 1010
- Question 1: "Find Mass to Light ratio"
- Interpretting data (guided)
- The WOW moment (if it didn't happen while plotting)
- Question 2: "Explain integrated SB plot."
- Understand what you've plotted
- We want to include everything inside of a given radius to be consistent between mass and luminosity
- Question 3: "Reason out how M:L ratio varies"
- Lower mass stars are way less brighter than sun
- Why did we choose 2 solar masses for 1 solar luminosity?
- Possibly: What does mass to light ratio really mean? It's comparison of 2 masses, kind of guess work to figure out how much mass we can assign to each solar luminosity we see
- Question 4: "Why can't we use these two galaxies?"
- Understanding galaxy orientations: face-on vs. edge-on
- More Doppler shift practice (part a)
- Read directions, thoughts about how dust blocks light (part b)
- Question 5: "What do you think about the whole thing?"
- Get them to be skeptical, know that it's OK to express their personal opinions about science
- Basically, this is a chance to work with galaxies and give the kids a chance to understand a bit more about galaxies.