Warm Up Friday , May 10, 2013

1. Warm Up Friday, May 10, 2013 Imagine an star about 1.5 times the size of our sun being condensed into a star with the diameter of the city of Santa Ana. How can all that matter get packed into a space so tight? Hint: Think about the structure of atoms. Not to scale!!

2. Agenda • Warm Up • Correct HW • 15.3 Notes • Bill Nye “Outer Space” • Cool Down

3. 15.3 Lives of Stars • Stars don’t live forever • We use the words, “birth” and “death,” but remember stars are not living organisms

4. Beginnings of a Star • Stars are born in nebulas • Nebula – large cloud of gas, dust and plasma Pillars of Creation

6. Protostar • When enough gas and dust gets pulled together by gravitational forces, a protostar, or begins to form. • You can compare this to an unborn human.

7. Birth of a Star • When the gas and dust becomes so dense that nuclear fusion starts, a star is born! • E=mc2, the secret of the stars!

8. Effect of Mass • Smaller stars live longer than larger ones because larger ones use up all their hydrogen for fusion sooner. • During this mid-life time, you will find the star in the main sequenceon a H-R Diagram • Which do you expect to live longer – our Sun or Betelgeuse?

10. Video Clip • The Universe: Life and Death of a Star 0:00-12:00 min

11. Death of Stars • Path taken depends on mass

12. Low & Medium Mass Stars • As fuel runs out, core shrinks and outer layers expand. This is called a Red Giant. • As outer layers expand even more, a Red Giant become a Planetary Nebula

13. White Dwarfs • Blue/white cores left behind by a planetary nebula • About the size of earth • Think of these as “retired stars”

14. High Mass Stars • Near the end of their (shorter) life, high mass stars become supergiants. • The supergiant then explodes in a huge burst of light known as a supernova.

15. So, fusion can produce helium from hydrogen, but heavy elements are produced in supernova explosions. • If high mass stars didn’t die, we would only have 2 or 3 boxes on our periodic table!!

16. We are Stardust • Suppose you eat some spinach for dinner tonight. The spinach contains iron that is taken up by hemoglobin in your blood. • All those iron atoms…they were made in a supernova explosion! • In other words, massive stars had to die for us to experience life. The universe recycles! • We are literally stardust. The Universe Exists Within Us

17. Neutron Stars • Form after a supernova • Contain the remains of high-mass stars • Smaller and denser than White Dwarfs

18. Pulsars • Short for “pulsating radio sources” • When they were first detected by radio telescopes, people called the unknown source LGM for “little green men” ;) • They are actually spinning neutron stars Radio waves we collect

19. Black Holes • The most massive stars may become black holes • So much mass gets packed into such a tight space that the gravitational force it exerts pulls in everything, even light and other electromagnetic radiation. • Since black holes don’t let any electromagnetic radiation escape, we can’t observe them directly. We infer their presence from the effect of their gravity on other objects. **If your superhero is from a black hole, he/she needs to manipulate gravity just to escape.

21. Which stars are the oldest?

22. Cool Down • Title” Life Cycle of a Star Flow Map • 15.3 Vocabulary Booklet (8 words) • P. 613 #1a-c, #2a-b, & #3a-c Homework