Stars

TEKS 8.9A, 8.2B

Stars

KEY IDEAS

•What is the life cycle of a star?

•What is a Hertzsprung-Russell diagram?

•How can you use a Hertzsprung-Russell
diagram to compare and classify stars?

Words to Know

star

light-year

luminosity

Hertzsprung-Russell diagram

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Copyright © Savvas Learning Company LLC. All Rights Reserved. Savvas is not responsible for any modifications made by end users to the content posted in its original format.

What is the life cycle of a star?

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What is the life cycle of a star? continued

A star is a giant ball of hot gas, mainly composed of hydrogen and
helium. A light-year is the distance that a star’s light travels in one year.

All stars have a life cycle in which they form, develop, and cease to shine
when they run out of fuel.

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Our Sun’s Life Cycle

SEP Use Models Use the images from the picture bank to
complete the diagram of the life cycle of the sun.

Picture
Bank

A. Planetary

Nebula

B. White Dwarf

C. Red Giant

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Our Sun’s Life Cycle Answers

SEP Use Models Use the images from the picture bank to
complete the diagram of the life cycle of the sun.

Picture
Bank

A. Planetary

Nebula

B. White Dwarf

C. Red Giant

C

A

B

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What is an H-R diagram?

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What is an H-R diagram? continued

A star’s temperature is related to
its luminosity, the amount of
energy it emits from its surface.

The Hertzsprung-Russell
diagram, or H-R diagram, is a
graph that shows the temperature
and luminosity of different stars.

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How can you use a Hertzsprung-Russell
diagram to compare and classify stars?

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Use H-R Diagrams

THEME Patterns Classify the types of stars on the H-R diagram
as white dwarfs, giants, supergiants, or main-sequence.

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Use H-R Diagrams Answers

THEME Patterns Classify the types of stars on the H-R diagram
as white dwarfs, giants, supergiants, or main-sequence.

Supergiants

Main-sequence

White dwarfs

Giants

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Star Statements

Analyze Correct each false statement so that it is true.

1. A Hertzsprung-Russell diagram is a graph of stars with

temperature on the x-axis and color on the y-axis.

2. The region of the H-R diagram that most stars fall within

is the giant sequence.

3. For most stars, their surface temperature decreases as

their luminosity increases.

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Star Statements Answers

Analyze Correct each false statement so that it is true.

1. A Hertzsprung-Russell diagram is a graph of stars with

temperature on the x-axis and color on the y-axis.

A Hertzsprung-Russell diagram is a graph of stars with
temperature on the x-axis and luminosity on the y-axis.

2. The region of the H-R diagram that most stars fall within

is the giant sequence.

The region of the H-R diagram that most stars fall within is
the main sequence.

3. For most stars, their surface temperature decreases as

their luminosity increases.

For most stars, their surface temperature increases as their
luminosity increases.

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Exit Ticket

Choose one of the following ways to
compare the life cycle of the sun with
that of a more massive star outside the
main sequence.

1.

Write 2–3 paragraphs about each
star’s life, and then read it to the
class.

2.

Use a pad of paper or sticky notes to
draw a flipbook illustrating how each
star changes during its life cycle.