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The Solar Spectrum: Sun's Composition and Surface Temperature

Explore the composition of the Sun and its surface temperature, as well as the energy source, transport, and structure of its interior. Discover the different layers of the Sun's atmosphere and learn about solar activity such as sunspots, solar magnetism, and prominences.

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The Solar Spectrum: Sun's Composition and Surface Temperature

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  1. Outline of The Sun (Ch. 10)(Not exactly like the book) The Solar Spectrum: Sun’s composition and surface temperature Sun’s Interior: Energy source,energy transport, structure, helioseismology. Sun’s Atmosphere: Photosphere, chromosphere, corona Solar Activity: Sunspots, solar magnetism, solar cycle, prominences and flares.

  2. I. Solar Spectrum: Composition and Surface Temperature

  3. 76 22

  4. I. Solar Spectrum: How do we know the composition of the Sun?

  5. I. Solar Spectrum: How do we know the composition of the Sun? What type of Spectrum is this?

  6. Surface Temperature: approximately 6,000 K How do we know this?

  7. Outline of The Sun (Ch. 10) The Solar Spectrum: Sun’s composition and surface temperature Sun’s Interior: Energy source,energy transport, structure, helioseismology. Sun’s Atmosphere: Photosphere, chromosphere, corona Solar Activity: Sunspots, solar magnetism, solar cycle, prominences and flares.

  8. Question 1 What is the source of the Sun’s energy? a) Chemical reactions b) Gravitational contraction c) Nuclear fission (like in nuclear power plants) d) Nuclear fusion

  9. Why does the Sun shine?

  10. Is it on FIRE? Fuel Rate of burning that fuel

  11. Is it on FIRE? Chemical Energy Content ~ 10,000 years Luminosity

  12. Is it on FIRE? … NO! Chemical Energy Content ~ 10,000 years Luminosity

  13. Is it CONTRACTING?

  14. Is it CONTRACTING? Gravitational Potential Energy ~ 25 million years Luminosity

  15. Is it CONTRACTING? … NO! Gravitational Potential Energy ~ 25 million years Luminosity

  16. E = mc2 - Einstein, 1905

  17. Is it powered by NUCLEAR ENERGY? Nuclear Potential Energy (core) ~ 10 billion years Luminosity

  18. Is it powered by NUCLEAR ENERGY? … YES! Nuclear Potential Energy (core) ~ 10 billion years Luminosity

  19. Question 1 What is the source of the Sun’s energy? a) Chemical reactions b) Gravitational contraction c) Nuclear fission (like in nuclear power plants) d) Nuclear fusion

  20. Fusion Small nuclei stick together to make a bigger one (Sun, stars) Fission Big nucleus splits into smaller pieces (Nuclear power plants)

  21. Hydrogen Fusion into Helium in the Sun’s Core 4 protons  one Helium nucleus + Energy

  22. Hydrogen Fusion into Helium in the Sun’s Core 4 protons  one helium nucleus + Energy The mass of the four protons is higher than that of the helium nucleus where did the missing mass go?

  23. Hydrogen Fusion into Helium in the Sun’s Core 4 protons  one helium nucleus + Energy The mass of the four protons is higher than that of the helium nucleus where did the missing mass go? The mass became energy, and E=mc2 so a little mass can produce a lot of energy

  24. Proton-proton chain is how hydrogen fuses into helium in Sun

  25. • Sun’s interior

  26. Core: Energy generated by nuclear fusion

  27. Radiation Zone: Energy transported upward by photons

  28. Convection Zone: Energy transported upward by rising hot gas

  29. In the Sun, gravity is balanced by outward pressure (due to the outflow of energy)

  30. Solar Thermostat Temperature Decreases Temperature Restored Fusion Rate Decreases Core compresses

  31. Solar Thermostat Temperature Increases Temperature Restored Fusion Rate Increases Core expands

  32. By studying the motion of the Sun’s surface we can learn about its interior in a similar way to the study of Earthquakes. Helioseismology

  33. What have we learned? • How does the solar thermostat work? • There is a equilibrium between gravity and energy outflow……. • How does the energy from fusion get out of the Sun? • Energy is produces in the core by nuclear fusion and it gets radiated outward. The convection zone carries energy the rest of the way to the photosphere, where it is radiated into space as sunlight. • How do we know what is happening inside the Sun? • Helioseismology and other techniques

  34. Outline of The Sun (Ch. 10) The Solar Spectrum: Sun’s composition and surface temperature Sun’s Interior: Energy source,energy transport, structure, helioseismology. Sun’s Atmosphere: Photosphere, chromosphere, corona Solar Activity: Sunspots, solar magnetism, solar cycle, prominences and flares.

  35. Photosphere: Visible surface of Sun T ~ 6,000 K

  36. Chromosphere: Middle layer of solar atmosphere

  37. Corona: Outermost layer of solar atmosphere

  38. Solar Granulation in the Photosphere

  39. Convection (rising hot gas) takes energy to surface

  40. Cloud tops on Earth produced by convection: warm air rises

  41. Sunspots

  42. Sunspots and Solar Rotation

  43. Question Why do sunspots look dark? a) They are dark clouds b) They are smoke from the Sun’s interior c) They are cooler than the rest of the Sun’s surface d) None of the above

  44. Question Why do sunspots look dark? a) They are dark clouds b) They are smoke from the Sun’s interior c) They are cooler than the rest of the Sun’s surface d) None of the above

  45. Loops trace magnetic field lines

  46. Review from Ch 5 Blackbody radiation: The hotter the brighter The hotter the bluer Why do sunspots look dark? They are cooler than the rest of the Sun’s surface Are they redder?

  47. Sunspots

  48. Solar Chromosphere Visible during a total solar eclipse

  49. Solar Chromosphere

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