1. © 2006 Pearson Prentice Hall Lecture Outlines PowerPoint Chapter 24 Earth Science 11e Tarbuck/Lutgens Modified for educational purposes only By S. Koziol 12-8-2010

2. Earth Science, 11e Beyond Our Solar System Chapter 24

3. 24.1 Properties of stars  Distance Measuring a star's distance can be very difficult Measuring a star's distance can be very difficult Stellar parallax Stellar parallax Used for measuring distance to a star Used for measuring distance to a star Apparent shift in a star's position due to the orbital motion of Earth Apparent shift in a star's position due to the orbital motion of Earth Measured as an angle Measured as an angle Near stars have the largest parallax Near stars have the largest parallax Largest parallax is less than one second of arc Largest parallax is less than one second of arc

4. 24. 1 Properties of stars 24. 1 Properties of stars (continued)  Distance Distances to the stars are very large Distances to the stars are very large Units of measurement Units of measurement Kilometers or astronomical units are too cumbersome to use Kilometers or astronomical units are too cumbersome to use Light-year is used most often Light-year is used most often Distance that light travels in 1 year Distance that light travels in 1 year One light-year is 9.5 trillion km (5.8 trillion miles) One light-year is 9.5 trillion km (5.8 trillion miles) Other methods for measuring distance are also used Other methods for measuring distance are also used

5. 24. 1 Properties of stars 24. 1 Properties of stars (continued)  Stellar brightness Controlled by three factors Controlled by three factors Size Size Temperature Temperature Distance Distance Magnitude Magnitude Measure of a star's brightness Measure of a star's brightness

6. 24.1 Properties of stars 24.1 Properties of stars (continued)  Stellar brightness Magnitude Magnitude Two types of measurement Two types of measurement Apparent magnitude Apparent magnitude Brightness when a star is viewed from Earth Brightness when a star is viewed from Earth Decreases with distance Decreases with distance Numbers are used to designate magnitudes - dim stars have large numbers and negative numbers are also used Numbers are used to designate magnitudes - dim stars have large numbers and negative numbers are also used

7. 24.1 Properties of stars 24.1 Properties of stars (continued)  Stellar brightness Magnitude Magnitude Two types of measurement Two types of measurement Absolute magnitude Absolute magnitude "True" or intrinsic brightness of a star "True" or intrinsic brightness of a star Brightness at a standard distance of 32.6 light-years Brightness at a standard distance of 32.6 light-years Most stars' absolute magnitudes are between -5 and +15 Most stars' absolute magnitudes are between -5 and +15

8. 24.1 Properties of stars 24.1 Properties of stars (continued)  Color and temperature Hot star Hot star Temperature above 30,000 K Temperature above 30,000 K Emits short-wavelength light Emits short-wavelength light Appears blue Appears blue Cool star Cool star Temperature less than 3000 K Temperature less than 3000 K Emits longer-wavelength light Emits longer-wavelength light Appears red Appears red

9. 24.1 Properties of stars 24.1 Properties of stars (continued)  Color and temperature Between 5000 and 6000 K Between 5000 and 6000 K Stars appear yellow Stars appear yellow e.g., Sun e.g., Sun  Binary stars and stellar mass Binary stars Binary stars Two stars orbiting one another Two stars orbiting one another Stars are held together by mutual gravitation Stars are held together by mutual gravitation Both orbit around a common center of mass Both orbit around a common center of mass

10. 24.1 Properties of stars 24.1 Properties of stars (continued)  Binary stars and stellar mass Binary stars Binary stars Visual binaries are resolved telescopically Visual binaries are resolved telescopically More than 50% of the stars in the universe are binary stars More than 50% of the stars in the universe are binary stars Used to determine stellar mass Used to determine stellar mass Stellar mass Stellar mass Determined using binary stars – the center of mass is closest to the most massive star Determined using binary stars – the center of mass is closest to the most massive star

11. Binary stars orbit each other around their common center of mass Figure 24.4

12. 24.1 Properties of stars 24.1 Properties of stars (continued)  Binary stars and stellar mass Stellar mass Stellar mass Mass of most stars is between one-tenth and fifty times the mass of the Sun Mass of most stars is between one-tenth and fifty times the mass of the Sun

13. 24.1 Hertzsprung-Russell diagram  Shows the relation between stellar Brightness (absolute magnitude) and Brightness (absolute magnitude) and Temperature Temperature  Diagram is made by plotting (graphing) each star's Luminosity (brightness) and Luminosity (brightness) and Temperature Temperature

14. 24.1 Hertzsprung-Russell diagram 24.1 Hertzsprung-Russell diagram (continued)  Parts of an H-R diagram Main-sequence stars Main-sequence stars 90% of all stars 90% of all stars Band through the center of the H-R diagram Band through the center of the H-R diagram Sun is in the main-sequence Sun is in the main-sequence Giants (or red giants) Giants (or red giants) Very luminous Very luminous Large Large Upper-right on the H-R diagram Upper-right on the H-R diagram

15. 24.1 Hertzsprung-Russell diagram 24.1 Hertzsprung-Russell diagram (continued)  Parts of an H-R diagram Giants (or red giants) Giants (or red giants) Very large giants are called supergiants Very large giants are called supergiants Only a few percent of all stars Only a few percent of all stars White dwarfs White dwarfs Fainter than main-sequence stars Fainter than main-sequence stars Small (approximate the size of Earth) Small (approximate the size of Earth) Lower-central area on the H-R diagram Lower-central area on the H-R diagram Not all are white in color Not all are white in color Perhaps 10% of all stars Perhaps 10% of all stars

16. Idealized Hertzsprung- Russell diagram Figure 24.5

17. Quiz Break

18. 24.2 Variable stars  Stars that fluctuate in brightness  Types of variable stars Pulsating variables Pulsating variables Fluctuate regularly in brightness Fluctuate regularly in brightness Expand and contract in size Expand and contract in size Eruptive variables Eruptive variables Explosive event Explosive event Sudden brightening Sudden brightening Called a nova Called a nova

19. 24.2 Interstellar matter  Between the stars is "the vacuum of space"  Nebula Cloud of dust and gases Cloud of dust and gases Two major types of nebulae Two major types of nebulae Bright nebula Bright nebula Glows if it close to a very hot star Glows if it close to a very hot star Two types of bright nebulae Two types of bright nebulae Emission nebula Emission nebula Reflection nebula Reflection nebula

20. The Orion Nebula is a well- known emission nebula Figure 24.8

21. A faint blue reflection nebula in the Pleiades star cluster Figure 24.9

22. 24.2 Interstellar matter 24.2 Interstellar matter (continued)  Nebula Two major types of nebulae Two major types of nebulae Dark nebula Dark nebula Not close to any bright star Not close to any bright star Appear dark Appear dark Contains the material that forms stars and planets Contains the material that forms stars and planets

23. 24.2 Stellar evolution  Stars exist because of gravity  Two opposing forces in a star are Gravity – contracts Gravity – contracts Thermal nuclear energy – expands Thermal nuclear energy – expands  Stages Birth Birth In dark, cool, interstellar clouds In dark, cool, interstellar clouds Gravity contracts the cloud Gravity contracts the cloud Temperature rises Temperature rises Radiates long-wavelength (red) light Radiates long-wavelength (red) light Becomes a protostar Becomes a protostar

24. 24.2 Stellar evolution 24.2 Stellar evolution (continued)  Stages Protostar Protostar Gravitational contraction of gaseous cloud continues Gravitational contraction of gaseous cloud continues Core reaches 10 million K Core reaches 10 million K Hydrogen nuclei fuse Hydrogen nuclei fuse Become helium nuclei Become helium nuclei Process is called hydrogen burning Process is called hydrogen burning Energy is released Energy is released Outward pressure increases Outward pressure increases Outward pressure balanced by gravity pulling in Outward pressure balanced by gravity pulling in Star becomes a stable main-sequence star Star becomes a stable main-sequence star

25. 24.2 Stellar evolution 24.2 Stellar evolution (continued)  Stages Main-sequence stage Main-sequence stage Stars age at different rates Stars age at different rates Massive stars use fuel faster and exist for only a few million years Massive stars use fuel faster and exist for only a few million years Small stars use fuel slowly and exist for perhaps hundreds of billions of years Small stars use fuel slowly and exist for perhaps hundreds of billions of years 90% of a star's life is in the main-sequence 90% of a star's life is in the main-sequence

26. 24.2 Stellar evolution 24.2 Stellar evolution (continued)  Stages Red giant stage Red giant stage Hydrogen burning migrates outward Hydrogen burning migrates outward Star's outer envelope expands Star's outer envelope expands Surface cools Surface cools Surface becomes red Surface becomes red Core is collapsing as helium is converted to carbon Core is collapsing as helium is converted to carbon Eventually all nuclear fuel is used Eventually all nuclear fuel is used Gravity squeezes the star Gravity squeezes the star

27. 24.2 Stellar evolution 24.2 Stellar evolution (continued)  Stages Burnout and death Burnout and death Final stage depends on mass Final stage depends on mass Possibilities Possibilities Low-mass star Low-mass star 0.5 solar mass 0.5 solar mass Red giant collapses Red giant collapses Becomes a white dwarf Becomes a white dwarf

28. 24.2 Evolutionary stages of low mass stars Figure 24.12 A

29. 24.2 Stellar evolution 24.2 Stellar evolution (continued)  Stages Burnout and death Burnout and death Final stage depends on mass Final stage depends on mass Possibilities Possibilities Medium-mass star Medium-mass star Between 0.5 and 3 solar masses Between 0.5 and 3 solar masses Red giant collapses Red giant collapses Planetary nebula forms Planetary nebula forms Becomes a white dwarf Becomes a white dwarf

30. 24.2 Evolutionary stages of medium mass stars Figure 24.12 B

31. H-R diagram showing stellar evolution Figure 24.11

32. 24.2 Stellar evolution 24.2 Stellar evolution (continued)  Stages Burnout and death Burnout and death Final stage depends on mass Final stage depends on mass Possibilities Possibilities Massive star Massive star Over 3 solar masses Over 3 solar masses Short life span Short life span Terminates in a brilliant explosion called a supernova Terminates in a brilliant explosion called a supernova Interior condenses Interior condenses May produce a hot, dense object that is either a neutron star or a black hole May produce a hot, dense object that is either a neutron star or a black hole

33. 24.2 Evolutionary stages of massive stars Figure 24.12 C

34. 24.2 Stellar remnants  White dwarf Small (some no larger than Earth) Small (some no larger than Earth) Dense Dense Can be more massive than the Sun Can be more massive than the Sun Spoonful weighs several tons Spoonful weighs several tons Atoms take up less space Atoms take up less space Electrons displaced inward Electrons displaced inward Called degenerate matter Called degenerate matter Hot surface Hot surface Cools to become a black dwarf Cools to become a black dwarf

35. 24.2 Stellar remnants 24.2 Stellar remnants (continued)  Neutron star Forms from a more massive star Forms from a more massive star Star has more gravity Star has more gravity Squeezes itself smaller Squeezes itself smaller Remnant of a supernova Remnant of a supernova Gravitational force collapses atoms Gravitational force collapses atoms Electrons combine with protons to produce neutrons Electrons combine with protons to produce neutrons Small size Small size

36. 24.2 Stellar remnants 24.2 Stellar remnants (continued)  Neutron star Pea size sample Pea size sample Weighs 100 million tons Weighs 100 million tons Same density as an atomic nucleus Same density as an atomic nucleus Strong magnetic field Strong magnetic field First one discovered in early 1970s First one discovered in early 1970s Pulsar (pulsating radio source) Pulsar (pulsating radio source) Found in the Crab nebula (remnant of an A.D. 1054 supernova) Found in the Crab nebula (remnant of an A.D. 1054 supernova)

37. Crab Nebula in the constellation Taurus Figure 24.14

38. 24.2 Stellar remnants 24.2 Stellar remnants (continued)  Black hole More dense than a neutron star More dense than a neutron star Intense surface gravity lets no light escape Intense surface gravity lets no light escape As matter is pulled into it As matter is pulled into it Becomes very hot Becomes very hot Emits x-rays Emits x-rays Likely candidate is Cygnus X-1, a strong x- ray source Likely candidate is Cygnus X-1, a strong x- ray source

39. Quiz Break

40. 24.3 Galaxies  Milky Way galaxy Structure Structure Determined by using radio telescopes Determined by using radio telescopes Large spiral galaxy Large spiral galaxy About 100,000 light-years wide About 100,000 light-years wide Thickness at the galactic nucleus is about 10,000 light-years Thickness at the galactic nucleus is about 10,000 light-years Three spiral arms of stars Three spiral arms of stars Sun is 30,000 light-years from the center Sun is 30,000 light-years from the center

41. Face-on view of the Milk Way Galaxy Figure 24.18 A

42. Edge-on view of the Milk Way Galaxy Figure 24.18 B

43. 24.3 Galaxies 24.3 Galaxies (continued)  Milky Way galaxy Rotation Rotation Around the galactic nucleus Around the galactic nucleus Outermost stars move the slowest Outermost stars move the slowest Sun rotates around the galactic nucleus once about every 200 million years Sun rotates around the galactic nucleus once about every 200 million years Halo surrounds the galactic disk Halo surrounds the galactic disk Spherical Spherical Very tenuous gas Very tenuous gas Numerous globular clusters Numerous globular clusters

44. 24.3 Galaxies 24.3 Galaxies (continued)  Other galaxies Existence was first proposed in mid-1700s by Immanuel Kant Existence was first proposed in mid-1700s by Immanuel Kant Four basic types of galaxies Four basic types of galaxies Spiral galaxy Spiral galaxy Arms extending from nucleus Arms extending from nucleus About 30% of all galaxies About 30% of all galaxies Large diameter of 20,000 to 125,000 light years Large diameter of 20,000 to 125,000 light years Contains both young and old stars Contains both young and old stars e.g., Milky Way e.g., Milky Way

45. Great Galaxy, a spiral galaxy, in the constellation Andromeda Figure 24.20

46. 24.3 Galaxies 24.3 Galaxies (continued)  Other galaxies Four basic types of galaxies Four basic types of galaxies Barred spiral galaxy Barred spiral galaxy Stars arranged in the shape of a bar Stars arranged in the shape of a bar Generally quite large Generally quite large About 10% of all galaxies About 10% of all galaxies Elliptical galaxy Elliptical galaxy Ellipsoidal shape Ellipsoidal shape About 60% of all galaxies About 60% of all galaxies Most are smaller than spiral galaxies; however, they are also the largest known galaxies Most are smaller than spiral galaxies; however, they are also the largest known galaxies

47. A barred spiral galaxy Figure 24.22

48. 24.3 Galaxies 24.3 Galaxies (continued)  Other galaxies Four basic types of galaxies Four basic types of galaxies Irregular galaxy Irregular galaxy Lacks symmetry Lacks symmetry About 10% of all galaxies About 10% of all galaxies Contains mostly young stars Contains mostly young stars e.g., Magellanic Clouds e.g., Magellanic Clouds

49. 24.3 Galaxies 24.3 Galaxies (continued)  Galactic cluster Group of galaxies Group of galaxies Some contain thousands of galaxies Some contain thousands of galaxies Local Group Local Group Our own group of galaxies Our own group of galaxies Contains at least 28 galaxies Contains at least 28 galaxies Supercluster Supercluster Huge swarm of galaxies Huge swarm of galaxies May be the largest entity in the universe May be the largest entity in the universe

50. Quiz Break

51. 24.4 Red shifts  Doppler effect Change in the wavelength of light emitted by an object due to its motion Change in the wavelength of light emitted by an object due to its motion Movement away stretches the wavelength Movement away stretches the wavelength Longer wavelength Longer wavelength Light appears redder Light appears redder Movement toward “squeezes” the wavelength Movement toward “squeezes” the wavelength Shorter wavelength Shorter wavelength Light shifted toward the blue Light shifted toward the blue

52. 24.4 Red shifts 24.4 Red shifts (continued)  Doppler effect Amount of the Doppler shift indicates the rate of movement Amount of the Doppler shift indicates the rate of movement Large Doppler shift indicates a high velocity Large Doppler shift indicates a high velocity Small Doppler shift indicates a lower velocity Small Doppler shift indicates a lower velocity  Expanding universe Most galaxies exhibit a red Doppler shift Most galaxies exhibit a red Doppler shift Moving away Moving away

53. Raisin bread analogy of an expanding universe Figure 24.24

54. 24.4 Red shifts 24.4 Red shifts (continued)  Expanding universe Most galaxies exhibit a red Doppler shift Most galaxies exhibit a red Doppler shift Far galaxies Far galaxies Exhibit the greatest shift Exhibit the greatest shift Greater velocity Greater velocity Discovered in 1929 by Edwin Hubble Discovered in 1929 by Edwin Hubble Hubble's Law – the recessional speed of galaxies is proportional to their distance Hubble's Law – the recessional speed of galaxies is proportional to their distance Accounts for red shifts Accounts for red shifts

55. 24.4 Big Bang theory  Accounts for galaxies moving away from us  Universe was once confined to a "ball" that was Supermassive Supermassive Dense Dense Hot Hot

56. 24.4 Big Bang theory 24.4 Big Bang theory (continued)  Big Bang marks the inception of the universe Occurred about 15 billion years ago Occurred about 15 billion years ago All matter and space was created All matter and space was created  Matter is moving outward  Fate of the universe Two possibilities Two possibilities Universe will last forever Universe will last forever Outward expansion sill stop and gravitational; contraction will follow Outward expansion sill stop and gravitational; contraction will follow

57. 24.4 Big Bang theory 24.4 Big Bang theory (continued)  Fate of the universe Final fate depends on the average density of the universe Final fate depends on the average density of the universe If the density is more than the critical density, then the universe would contract If the density is more than the critical density, then the universe would contract Current estimates point to less then the critical density and predict an ever-expanding, or open, universe Current estimates point to less then the critical density and predict an ever-expanding, or open, universe

58. Chapter 24Test Guidance You will be responsible on the test for answering 3 of the following 6 questions. 1. What causes the difference between a star’s apparent magnitude and it absolute magnitude. 2. List and explain the three factors that control the apparent brightness of a star as seen from Earth. 3. Describe how binary stars are used to determine stellar mass. 4. List and describe the four basic types of galaxies. 5. What is Hubble’s Law, please explain in detail. 6. Briefly describe the Big Bang Theory (not the TV show).

59. End of Chapter 24