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Transcript
Life Cycle of a Star
8.8A describe components of the universe, including stars,
nebulae, and galaxies, and use models such as the
Herztsprung-Russell diagram for classification.
Essential Questions
1.
How do stars change over time?
2.
How are stars classified on a
Herztsprung-Russell Diagram?
3.
How does our sun compare to
other stars in the universe?
Objectives
1. Describe objects in space such as
stars (in all life stages) and galaxies.
2. Describe the life cycle of a star and
correlate a star’s life stage to its
placement on the HR-Diagram.
3. Classify the types of stars on the HRDiagram.
Warm Up

Look at the page:
Supernova in Chaco Canyon
-What predictions can you make about the
words SUPERNOVA and NEBULA?
-Record your predictions in your Interactive
Notebook.
ENGAGE: Life Cycle of a Human

Humans change through time. Describe the
Life Cycle of a Human
-Record at least 4 Stages in your Notebook.
-Include the length of the stages and important
details about each stage.
Human Life Cycle
EXPLORE: Life Cycles of Stars
Each Group will get a packet of pictures
taken from the Hubble Telescope.
YOUR TASK
-Read the descriptions on each picture.
-Use clues from what you read to try to
construct a “Life Cycle” for the star you have.
-Be prepared to share your groups ideas!

Warm Up: QUICK WRITE
Record the Chart in your Notebook and fill it in using what you
learned yesterday about how stars change over time.
TOPIC: Life Cycle of a Star: Stars Change Over Time
Key Points:
Questions I Still Have:
Space School: Stars

Stars
EXPLAIN: Life Cycle Foldable
Use pg 717 to illustrate your Life Cycle Foldable. Read
pgs. 716-719 to record information about each phase.
Nebula
Average Star
Red Giant
Planetary
Nebula
White Dwarf
Super Red
Giant
Supernova
Neutron Star
or Black Hole
(low mass star)
Nebula
Massive Star
(high mass
star)
Life Cycle of a Star

The changes that a star goes through is
determined by how much mass the star has.
Two Types of Life Cycles:
Average Star- a star with relatively low mass
Massive Star- a star with relatively high mass
Life Cycle of Stars
http://www.seasky.org/cosmic/sky7a01.html
Stellar Nebula


All stars begin in a
cloud of gas and dust
called a stellar
NEBULA.
Gravity will cause the
nebula to contract.
The nebula will break
into smaller pieces.
These pieces will
eventually form stars.
The Life of an Average Star


An Average Star (low mass
star) is condensed in a nebula
and begins a nuclear reaction
that causes hydrogen to form
helium, releasing energy in the
form of heat and light.
A low mass star will stay in this
MAIN SEQUENCE phase for a
long time, until it begins to use
up all of it’s hydrogen.
The Life of an Average Star


Towards the end of it’s
MAIN SEQUENCE
phase, a star begins to
burn all of its hydrogen.
The outer layers will
collapse, become
heated by the core and
expand out forming a
red giant.
The Life of an Average Star


The star begins to
quickly blow off its
layers forming a cloud
around the star called a
planetary nebula.
The star in the center of
the nebula is very hot
but not very bright.
The Life of an Average Star


When a star has
burned all it’s fuel it will
collapse under the
pressure of gravity.
The white dwarf that
forms is very small and
dense.
Life of a Massive Star
http://www.seasky.org/cosmic/sky7a01.html
Stellar Nebula


All stars begin in a
cloud of gas and dust
called a stellar
NEBULA.
Gravity will cause the
nebula to contract.
The nebula will break
into smaller pieces.
These pieces will
eventually form stars.
Life of a Massive Star


Stars with more mass
than the sun (high
mass stars) burn their
hydrogen faster than
low mass stars, so their
MAIN SEQUENCE
phase is much shorter.
These stars burn hotter
and brighter than low
mass stars.
Life of a Massive Star


When the high mass star
burns off it’s hydrogen its
outer layers begin to
expand rapidly.
Temperatures at the core
are much higher than a
red giant. Nuclear fusion
causes elements to
combine into an iron core
at amazing speeds.
Life of a Massive Star


The iron core collapses
on it’s self under the
intense gravity at very
high speeds.
The energy released is
called SUPERNOVA.
Life of a Massive Star


After the incredible release of
energy from the SUPERNOVA
a dense core (1 trillion times
denser than a white dwarf) is
all that remains of the Massive
Star.
If the mass is too dense it will
continue to collapse on itself
forming a black hole. The
gravitational pull of a black hole
is so great, light can not
escape.
Warm Up: Read to Learn

Read page 706 in your textbook.
-In your journals use the word Brightness in a
sentence.
-In your journals use the word magnitude in a
sentence.
The Hertzsprung-Russell (HR) Diagram

In groups, make observations about the HR
Diagram.
-In your Interactive Journal record and fill in the
following sentence:
I notice that _____________.

Record all observations made by your group.
MAGNITUDE: Brightness Increases from bottom to top
The Hertzsprung-Russell (HR) Diagram
Are these stars
brighter or dimmer
than the sun
1 L is equal to the
brightness of the sun
REMEMBER: Temperature Increases from right to left
Characteristics of Stars
The Hertzsprung-Russell (HR) Diagram

Temperature & Color
–
–
The color of a star indicates the T of the
star
Stars are classified by T
 Decreasing
T (bright to dim)
 O, B, A, F, G, K, M [Oh Be A Fine Girl, Kiss Me
]
http://www.seasky.org/cosmic/sky7a01.html
The Hertzsprung-Russell (HR) Diagram

Time to Practice: Challenge #1
-Use the Temperature and Magnitude
(brightness) on Each Star to place it on it’s
correct location on the HR Diagram.
The Hertzsprung-Russell (HR) Diagram
Time to Practice: Challenge #2
-Check your HR Diagram with the teacher.
Remove the stars and place them in the correct spot
on the Life Cycle of a Star Diagram.
-Make observations and inferences the relationship of
the HR Diagram to the Star’s Life Cycle.

Record your thoughts in your journal using the
sentence:
I notice that _________.
The Hertzsprung-Russell (HR) Diagram
http://www.dustbunny.com/afk/stars/lifecycle/hrdiagram.gif
Warm Up: Chaco Article

Read the Chaco Article
-Look back in your Interactive Notebook at your
first journal entry about Chaco.
-What predictions did you make. Record your
new understanding in your journal.
The Hertzsprung-Russell (HR) Diagram

Complete pg 112-114 in the Gateways book.
EVALUATE: RAFT Activity


Read the RAFT Instruction Sheet.
Work Silently to complete your RAFT by the end of
class.
Essential Questions
1.How do stars change over time?
2.How are stars classified on a
Herztsprung-Russell Diagram?
Objectives
Describe objects in space such as
stars (in all life stages) and galaxies.
Describe the life cycle of a star and
correlate a star’s life stage to its
placement on the HR-Diagram.