1. Stars

2. A Star is an object that produces energy at its core! A mass of plasma held together by its own gravity; Energy is released as electromagnetic radiation! Stars differ in size, age and temperature.

3. Star Power Stars are powered by nuclear fusion At 15 million degrees Celsius in the center of the star, fusion occurs. Very simplified: 4 Hydrogen  1 Helium + energy! E = mc 2

4. Fusion makes LOTS of energy E = mc 2 What do E and M symbolize? ….and “ c ” ….? E = Energy and m = mass c = the speed of light (300,000,000 m/s) Nuclear fusion

5. Astronomers learn about stars by studying their luminosity, spectrum, and motion

6. Life Cycle of the Stars

7. Stars are formed, changed, and recycled!

8. Stars A celestial body of hot gases that radiates energy from nuclear fusion occurring at the core. http://news.nationalgeographic.com/news/2007/10/images/071002-star-picture_big.jpg Milky Way, Nebula NGC 3603 20,000 light years away

9. _______ _____ is the distance light can travel in ONE YEAR. Light travels at a speed of 300,000,000 meters/second. Light Year 9,400,000,000,000,000 meters 9 quadrillion (9 thousand billion) http://www.nasa.gov/multimedia/imagegallery/image_feature_202.html Milky Way, NGC 3949, 50 million light years In one Second, light can travel around the Earth 10 times, according to one estimate.

10. Horesehead Nebula; 1500 light years distant http://www.nasa.gov/multimedia/imagegallery/image_feature_73.htm l http://www.nasa.gov/mission_pages/spitzer/news/spitzer- 20070212.html ____________: A dense cloud of gas and dust; the birthplace of stars. NEBULA

11. Bubble Nebula

12. Stingray Nebula

13. Horsehead Nebula

14. Red Square Nebula

15. Crab Nebula

16. Eye (of God) Nebula

17. Southern Crab Nebula

18. Eskimo Nebula

19. The nebula begins to contract due to __________. The pressure and temperature increase as a _____________ is formed. GRAVITY PROTOSTAR

20. When the temperature gets hot enough, _______________ begins and a _______ ____________ star is born. FUSION MAIN SEQUENCE Nuclear Fusion: The process of taking atom centers ( the nucleus) and fusing them together.

21. Throughout its life, these two forces determine the stages of a star ’ s life. Energy released from nuclear fusion counter-acts inward force of gravity. A Balancing Act

22. A star loses ____________ during fusion as energy is released. This decreases the star’s gravity. A star will expand, becoming a _______________. Very massive stars become ________ _____ _________. MASS RED GIANT http://www.universetoday.com/2008/01/31/will-earth-survive-when-the-sun-becomes-a-red-giant/ http://www.daviddarling.info/images/red_giant.gif SUPER RED GIANTS

24. As the fuel runs out in a average sized star, _________ slows down. The star will shrink in size, becoming a _________ _______. fusion A ____________ is a rotating white dwarf emitting radio waves. PULSAR White Dwarf

25. BLACK DWARVES http://chandra.harvard.edu/photo/2004/rxj1242/index.html http://www2.ph.ed.ac.uk/nuclear/photo/

26. A ___________________ is an _____________ that marks the end of a very massive star’s life. When it occurs, the exploding star can outshine all of the other stars in the galaxy in total for several days and may leave behind only a crushed core. SUPERNOVA explosion 1987 Supernova Large Magellanic Cloud 160,000 light years away Discovered by 14 year old Catherine Moore, on Nov. 7 2008.

27. Larger stars supernovae and form __________________. http://chandra.harvard.edu/photo/2004/rxj1242/index.html http://www2.ph.ed.ac.uk/nuclear/photo/

28. The most massive stars supernovae and form _________________ BLACK HOLES A black hole is an extremely massive remnant from which light can not escape. “Black holes are where God divided by zero” Stephen Wright

29. The Largest stars are red supergiants, 1500 times our sun. The smallest are red dwarfs, not much larger than Jupiter.

32. What makes some stars appear brighter? LUMINOSITY refers to the brightness ofstars. Because some stars are CLOSERor BIGGER, they may seem moreluminous. What makes some stars appear different colors? The temperature affects the color. Thehottest stars are blue, while the cooleststars are red.

33. Blue > 30,000 Kelvin Blue to blue white 10,000 -> 30,000 Kelvin White 7,500 -> 10,000 Kelvin Yellowish White 6,000 -> 7,500 Kelvin Yellow 5,200 -> 6,000 Kelvin Orange 3,700 -> 5,200 Kelvin Red 1,000 < 3,700 Kelvin Brown < 1,000 Kelvin Black 0 Kelvin

34. H-R diagram http://www.cosmosportal.eu/cosmos/tr/node/56058

35. Large, more massive stars have much more _____________ than the sun. This greater internal pressure causes fusion reactions to occur __________. This causes the largest stars to burn their fuel, and eventually run out, much more ______________. Larger stars live ___________ lives. Bigger stars are brighter and hotter due to the rapid rate of __________. Do larger stars or smaller stars last longer? Do hot stars or cool stars last longer? Large, more massive stars have much more _____________ than the sun. This greater internal pressure causes fusion reactions to occur __________. This causes the largest stars to burn their fuel, and eventually run out, much more ______________. Larger stars live ___________ lives. Bigger stars are brighter and hotter due to the rapid rate of __________. gravity quickly fusion shorter

36. All stars spend the majority of their lives fusing __________ into ________________: the main sequence. When all of the _____________ in the central regions is converted to helium, the star will begin to “burn” helium into _______________. Stars heavier than about 5 times the mass of the ______ can do this with no problem: they burn _____________, and then _______________, and then _____________, _______________, silicon, and so on…until Iron. hydrogen helium hydrogen carbon hydrogenhelium carbonoxygen

37. Iron is the lightest element that doesn’t release __________ when you attempt to fuse it together. You actually end up with less energy than you started with! So instead of generating pressure to hold up the outer layers, the iron fusion actually takes it out of the core. Thus, there is nothing left to combat ________________ from the outer layers. The result: ___________! energy gravity supernova Iron

38. This implosion (___________) happens very, very quickly: about 15 seconds. During the collapse, the nuclei in the outer parts of the star are pushed together, so close that elements heavier than __________ are formed. collapse Iron

39. Apparent Magnitude: How bright an object appears from Earth. Absolute Magnitude: How bright an object would appear from 32.6 light years away. Low numbers are brighter. Negative numbers are extremely bright.

40. The End.