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Module
4 - Exploration
Problem-Solving Activity: The HR Diagram .
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Name Eric Squires
Group Name Period
Now
that you know something about the relationship between temperature and color,
you are ready to explore more about the evolution of stars. Go to the HR
Diagram Simulator
at:
http://www .astro.ubc.ca/~scharein/a311/Sim/hr/HRdiaf!fam.html
This simulator shows information about
the mass, temperature and luminosity
(brightness) of
stars and shows how stars change with time. Use the simulator to answer the
following questions:
1. First, click the button labeled "100" one time to add one hundred stars to your diagram. The linear grouping that you see is called the main sequence.
a) Generally speaking, how does the
temperature of the blue stars compare to that of
the
red stars? The blue are hotter.
b) Generally speaking, how does the luI1,1inosity of the blue stars compare to that of
the
red stars? The blue are brighter.
2. Now click on an individual blue star
and write down its mass and main-sequence lifetime
Mass=8.27 Solar Masses
Main-sequence lifetime=31.3 million years
3. Do the same thing for a red star. "
4.
Explain, in general terms, what the relationship is between mass and
main-sequence
The lower the mass the greater the star life.
5. Now we are ready to start the
simulation. Click on the button labeled "Evolve"
a) Which stars leave the main sequence
first? The blue stars
b) The stars change color as they leave
the main sequence. What does this change indicate? It
shows the stars cooling down
c) Why do you think these changes take
place? The stars get old and cool down.
d) What do you suppose happens to stars after enough time goes by? The stars die.
6. Start the simulation again, but this time click on an individual star and keep track of its luminosity as the simulation progresses.
a) How does
luminosity change as the star leaves the main sequences? The luminosity
increases. b) Why do you suppose
is? The star gets brighter and bigger.