Download Unit 10 H-R Diagram Worksheet

Name __________________________
Date ___________
PS/ES Per ___
Mr. Williams
The H-R Diagram
Color this H-R diagram. Try to fade one color into another.
Star Facts:
1. Average-sized stars fuse Hydrogen into Helium. This process creates electromagnetic energy Ex: Light, Heat, X-rays
etc.
2. Most stars spend the bulk of their “lives” with a Luminosity and Temperature that places them in the MAIN
SEQUENCE region of the graph.
3. Stars form from clouds of space dust and gas (mostly hydrogen with some helium) called Nebulae. Gravity will start to
pull in the dust and gas so it begins to clump together, forming an unstable Protostar. When enough matter is pulled into
the center and enough heat is generated, nuclear fusion will begin and it is now a full fledged star in the Main Sequence.
Yes, the star is now a gigantic exploding nuclear energy furnace. Thanks, Sun!
4. Super-giant stars are called SUPERGIANTS. As BLUE SUPERGIANTS age, they swell and cool to become
YELLOW and RED SUPERGIANTS. When SUPERGIANTS reach old age, they go kablooey in a blaze of glory called
a supernova. Very exciting.
5. As MAIN SEQUENCE stars reach old age, they swell and cool to become RED GIANTS. When RED GIANTS run
out of hydrogen fuel, they shrink, get hotter and become WHITE DWARFS, hot remnants of the fusion of helium into
carbon. Once all the helium is used up, the white dwarf will cool to a BLACK DWARF. How boring.
Understanding the H-R diagram and star life cycles.
1. To which star group does Polaris belong? _________________________
2. Estimate the surface temperature of the Sun. ________________________
3. To what star group does the Sun belong? __________________________
4. What COLOR are the hottest stars? _______________________________
5. What color are the coolest stars? _________________________________
6. To what star group do most stars belong?
_______________________________________(Fact #2)
7. As the Sun ages, its temperature will change as it runs out of fuel. List the
order of star groups that the sun will join as it ages and “dies”. (Fact #5)
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8. State the relationship between temperature and luminosity for main
sequence stars. BE CAREFUL, look at the axis values.
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9. About how many times brighter than the Sun is Betelgeuse?
_________________________________
10. If Betelgeuse is so bright, why does the Sun appear brighter to us?
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11. White dwarfs are ___________________than Red Giants.
Hotter / Cooler
12. Procyon B is ____________________ than Aldebaran.
Hotter / Cooler
13. For main sequence stars, hotter is brighter (see #8). Explain then, how
Aldebaran is brighter than the hotter star, Sirius.
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