Life Cycle of a Star

1. 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.

2. 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.

3. 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.

4. Human Life Cycle

5. 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!

6. Warm Up: QUICK WRITERecord the Chart in your Notebook and fill it in using what you learned yesterday about how stars change over time.

7. Space School: Stars • Stars

8. EXPLAIN: Life Cycle FoldableUse pg 717 to illustrate your Life Cycle Foldable. Read pgs. 716-719 to record information about each phase.

9. 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

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

11. 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.

12. 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.

13. 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.

14. 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.

15. 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.

16. Life of a Massive Star http://www.seasky.org/cosmic/sky7a01.html

17. 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.

18. 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.

19. 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.

20. 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.

21. 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.

22. 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.

23. 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.

24. 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

25. 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 AFine Girl, Kiss Me ] http://www.seasky.org/cosmic/sky7a01.html

26. 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.

27. 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 _________.

28. The Hertzsprung-Russell (HR) Diagram http://www.dustbunny.com/afk/stars/lifecycle/hrdiagram.gif

29. 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.

30. The Hertzsprung-Russell (HR) Diagram • Complete pg 112-114 in the Gateways book.

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