The document discusses nucleosynthesis and the origins and life cycles of stars. It explains that elements were first formed in the early universe after the Big Bang as it cooled. Stars then formed from clouds of gas and dust, and nuclear fusion in their cores generated heavier elements. Stars have different classifications based on attributes like temperature, color, size and brightness. They are born, evolve through stages like red giants, and die, sometimes in supernovas. Their deaths leave behind remnants like neutron stars or black holes.

1. NUCLEOSYNTHESIS

2. WHERE DID ELEMENTS COME FROM?

3. Our universe started with a BIG BANG.

4. big bang n. ( cosmology ) the cosmic explosion that is hypothesized to have marked the origin of the universe.

5. After the BIG BANG , the universe started to e x p a n d .

6. The first seconds after the BIG BANG, it was very hot.

7. Then, the universe started to cool down.

8. Right after the BIG BANG, the p + , the n 0 and the e - were flying around without control.

9. When it started to cool down, the quarks started making primitive elements:

10. 1 H 1 Hydrogen, 1 proton

11. 1 H 2 Hydrogen, 1 proton, 1 neutron

12. 2 H 3 Helium, 2 protons, 1 neuron

13. 2 H 4 Helium, 2 protons, 2 neurons

14. Those elements started forming stars.

15. Star n. a self-luminous gaseous spherical celestial body of great mass which produces energy by means of nuclear fusion reactions .

16. In the stars, because of high pressure, the elements started bonding and forming heavier elements

17. HOW WILL WE END?

18. WE all star We all started with the BIG BANG…

19. … but how will we end?

20. Some scientists are sure that the universe will continue to expand forever.

21. However, there is a theory that our universe will end in “big crunch”

22. It states that someday the universe will stop expanding and crunch together.

23. There is no proof for that theory.

24. Classifying Stars . . . . . . . . . . . . . . . . . . . . . . . . .

25. TO RECOGNISE STARS, SCIENTISTS HAVE TO CLASSIFY THEM

26. STARS ARE CLASSIFIED BY

27. T E M P E R A T U R E

28. C O L O R

29. size size size size

30. brightness

31. If the star is blue , it means it is very hot . ( ≈50,000 C°)

32. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Cold stars are red . . . . . . . . . . . . . . . . . . . . . . . . . .

33. The bigger or hotter the star is, the brighter it is.

34. Brightness is measured in 2 ways:

35. apparent brightness (brightness seen from earth)

36. absolute brightness (the “real” brightness of the star)

37. Stars are mostly made out of hydrogen.

38. Helium is about ¼ of the stars’ composition.

39. Enjar Hertzsprung and Henry Norris Russell made a diagram that classifies stars.

40. The hertzsprung-russel diagram stars temperature size color of star

41. Scientists measure distance between stars using parallax

42. Parallax n. apparent change in apposition of an object when you look at it from different places

43. Scientists watch the positions of stars during different times of the year to figure out it’s position.

44. LIVES OF STARS

45. Stars do not live forever.

46. The larger a star is, the shorter its life is.

47. Stars are born in nebulas.

48. Nebula n. a large cloud of dust in space

49. Gravity pulls dust together so it forms a protostar

50. Protostar n. an early stage in the evolution of a star, after the beginning of the collapse of the gas cloud from which it is formed, but before sufficient contraction has occurred to permit initiation of nuclear reactions at its core.

51. As the protostar gets denser and denser, it forms a star

52. as the star becomes older, it becomes a red giant

53. red giant = star uses up its energy and becomes cooler, so it expands

54. Layers of the red giant fall off, releasing dust and gas into space.

55. It is called a planetary nebula.

56. The remaining star is very dense and bright .

57. It is a white dwarf .

58. When a white dwarf stops glowing, it is called a black dwarf.

59. high-mass stars are different .

60. When they die, they make a supernova – a giant explosion.

61. After the supernova, the star becomes either a neutron star or a black hole.

62. a neutron star : a white dwarf that has very high pressure and temperature

63. A black hole is a neutron star with gravity so strong that nothing, even light, can escape.

64. CAREERS

65. Nucleosynthesis is been studied by physicists and astronomers .

66. www.nasa.gov http://www.dictionary.net / big+bang http://dictionary.reference.com/browse/star http://www.wolaver.org / Space/abell39nebula.jpg https://segue.atlas.uiuc.edu / uploads/ryemm2/heic0409a.jpg http://www.janis.or.jp / users / kitahara / sww / rigel-z.jpg http://www.dorlingkindersley-uk.co.uk/static/clipart/uk/dk/sci_space/image_sci_space013.jpg http://www.mauthelimited.com / Assignments / Dreamweaver / Science_Class / Images / stars / whitedwarf_star.jpg http://cse.ssl.berkeley.edu / bmendez/ay10/2000/cycle / redgiant.gif

67. http://www.agdesktop.com/wallpaperspaceebulaebula-0006.jpg http://www.abc.net.au/unleashed/images/OpenBook_Stock_400.jpg http://techlibrarian.files.wordpress.com/2009/06/horsehead-nebula2.jpg