Life Cycle of a Star

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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 How do stars change over time? How are stars classified on a Herztsprung-Russell Diagram? 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 stars life stage to its placement on the HR-Diagram. 3. Classify the types of stars on the HR-Diagram.
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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.

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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.

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Human Life Cycle
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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!

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Warm Up QUICK WRITERecord 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 TOPIC Life Cycle of a Star Stars Change Over Time
Key Points Questions I Still Have

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Space School Stars

• Stars

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EXPLAIN Life Cycle FoldableUse pg 717 to
illustrate your Life Cycle Foldable. Read pgs.
716-719 to record information about each phase.
Nebula Average Star (low mass star) Red Giant Planetary Nebula White Dwarf
Nebula Massive Star (high mass star) Super Red Giant Supernova Neutron Star or Black Hole
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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

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Life Cycle of Stars
http//www.seasky.org/cosmic/sky7a01.html
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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.

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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 its hydrogen.

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The Life of an Average Star

• Towards the end of its 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.

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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.

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The Life of an Average Star

• When a star has burned all its fuel it will
  collapse under the pressure of gravity.
• The white dwarf that forms is very small and
  dense.

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Life of a Massive Star
http//www.seasky.org/cosmic/sky7a01.html
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Stellar Nebula
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.

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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.

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Life of a Massive Star

• When the high mass star burns off its 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.

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Life of a Massive Star

• The iron core collapses on its self under the
  intense gravity at very high speeds.
• The energy released is called SUPERNOVA.

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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.

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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.

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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.

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The Hertzsprung-Russell (HR) Diagram
MAGNITUDE Brightness Increases from bottom to top
1 L is equal to the brightness of the sun
Are these stars brighter or dimmer than the sun
REMEMBER Temperature Increases from right to left
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The Hertzsprung-Russell (HR) Diagram
Characteristics of Stars

• 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
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The Hertzsprung-Russell (HR) Diagram

• Time to Practice Challenge 1
• -Use the Temperature and Magnitude (brightness)
  on Each Star to place it on its correct location
  on the HR Diagram.

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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 Stars Life
  Cycle.
• Record your thoughts in your journal using the
  sentence I notice that _________.

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The Hertzsprung-Russell (HR) Diagram
http//www.dustbunny.com/afk/stars/lifecycle/hrdia
gram.gif
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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.

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The Hertzsprung-Russell (HR) Diagram

• Complete pg 112-114 in the Gateways book.

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EVALUATE RAFT Activity

• Read the RAFT Instruction Sheet.
• Work Silently to complete your RAFT by the end of
  class.

Essential Questions How do stars change over time? 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 stars life stage to its placement on the HR-Diagram.