Making a Final H-R Diagram
You now have enough data to make an H-R diagram for 3,803 stars. That's quite
a few more than the 52 stars you used in Exercises 1 and 2!
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Exercise 6. Use the graphing program to make an H-R diagram of the stars from the
Gliese Catalogue. Remember to calculate the distance (in parsecs) from the parallax
(in milliarcseconds). Create a new column in the spreadsheet with absolute
magnitude using the equation
Mabsolute = mapparent - 5 log d + 5.
Then make a graph with b-v color on the x-axis and absolute magnitude on the
y-axis. Don't forget to reverse the y-axis to put higher-luminosity stars
toward the top. If you don't know how to do these tasks in your graphing program,
see the virtualobservatory.org Graphing and Analyzing Data
tutorial.
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Question
14. Examine the diagram you just made. Compare it to the schematic
H-R diagram you saw earlier. What groups do you see in the new diagram?
Remember that the schematic diagram was just a theoretical guess, but the
diagram you made in Exercise 4 comes from real data! |
In this activity, you have learned what an H-R diagram is: a technique for
studying the life cycles of stars by graphing their luminosities and temperatures.
After making two simple diagrams, you used the NVO registry to search for data
appropriate for making a diagram with many more stars. You used VizieR to get
data from one survey, then created a graph of the data. So you have used real
astronomical tools to download real data, which you used to make a real diagram!
Congratulations!
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