(Engagement and Readiness)



ASTRONOMY ASSESSMENT PROBE
(Eliciting Prior Know
ledge)
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The temperatures included above represent ONLY the surface temperatures of stars. Dots represent stars but do NOT demonstrate the actual sizes of them. Absolute magnitude is defined as the brightness of a star as seen from 32.6 light years away from the earth.

(Exploration and Discovery)
Analysis:

1. a. What feature(s) distinguishes a supergiant star from a red giant?


b. Which stars are brighter, supergiants or red giants? How do you know?

2. Based on the HR diagram on the first page:
a. How are stars positioned on the diagram horizontally? Vertically?


b. What do stars in the top right have in common with stars in the bottom right?


c. What do all white dwarf stars have in common?


3. How do the absolute magnitude values vary for stars located in the main sequence? Speculate on why there is such a large variation in that group.

4. Where are most of the stars plotted on the HR diagram? Why?

5. Stars that have the same spectral class also have the same .






FACT #1: JUSTIFIED TRUE OR FALSE STATEMENTS
(Concept and Skill Development)

Indicate whether the following statement is true or false and explain your reasoning.
a. Each of the four groups of stars plotted on the HR diagram share similar absolute magnitudes and surface temperatures.



b. Stars in the upper right are very small and stars in the lower left are very large.



c. The surface temperature of stars directly corresponds to the size of the star.




(Concept and Skill Transfer)

Spectral Class vs. Absolute Magnitude

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Exercise:
1. Plot the following twelve stars on the HR Diagram on page 1. Don’t be concerned with the number after the letter for the spectral class.


2. a. Which of the four groups does our sun belong to?

b. What is the approximate surface temperature of our sun?

c. Our Sun has a surface temperature that is similar to that of a red supergiant. How is our sun different than a red supergiant?


3. The absolute magnitude of Canopus and Agena are the same. Explain the significance of that relation.


4. What happens to the brightness of main sequence stars as the surface temperature increases.? Explain.


5. Stars vary in size. Does the location of a star on the diagram relate to the
size of the star? Explain.




FACT #2: I USED TO THINK....BUT NOW I KNOW
(Reflection and Self-Assessment)

After students complete the exercise, students will compare their original thoughts on classifying stars with what they know now.
Students will be encouraged to describe how their ideas changed or how they became more detailed compared to what they know at the beginning of the lesson.







You're now on your way to understanding this:
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