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Chapter 16/Chapter17

Chapter 16/Chapter17. Questions of the Day. What are stars? What are their properties? Who was Annie Jump Cannon? Why was she important to the study of stars? What is stellar spectroscopy? What does it tell us about a star?

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Chapter 16/Chapter17

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  1. Chapter 16/Chapter17

  2. Questions of the Day • What are stars? What are their properties? • Who was Annie Jump Cannon? Why was she important to the study of stars? • What is stellar spectroscopy? What does it tell us about a star? • What is the Sun? Why is it important to study this particular star?

  3. Parallax of a Star

  4. Parallax of a Star

  5. Differential Magnitude

  6. Differential Magnitude • Two stars have a magnitude of 7 and 3. How much brighter is the star with a magnitude of 3 than the star with a magnitude of 7?

  7. Distance Modulus

  8. Distance Modulus

  9. Distance Modulus • A star has a absolute magnitude of -5 and a distance of 1000 parsecs. What is the magnitude of the star as view from Earth?

  10. Fig.16.09

  11. Annie Jump Cannon • 1863 – 1941 A.D. • Born in Delaware, grew up in Dover, Delaware. • Entered Wellsley College http://astro.wsu.edu/worthey/astro/html/im-women/04-cannon.jpg

  12. Annie Jump Cannon’s Work • Worked under Edward C. Pickering at Harvard University to classify spectra of stars • 1911 - 1914: Created the Henry Draper Catalogue • 1918: Doctorate Degree • 1914: Honorary in the Royal Astronomical Society

  13. Spectral Types http://blueox.uoregon.edu/~courses/BrauImages/Chap17/FG17_010.jpg

  14. Fig.16.18

  15. Fig.16.19

  16. Mass – Luminosity • A star has a mass of 5M, how much brighter is this star than the Sun?

  17. What is the Sun? • Our nearest star. • The center of our solar system. • The main engine for all the heat produced in the solar system.

  18. http://spaceflightnow.com/news/n0211/04soho/sun.jpg

  19. What are the properties of the sun? • Distance: 1.49 X 108 km = 1 A.U. • Size: 1.4 X 106 meter = 0.5° • Mass: 2 X 1030 kg • Density: 1.4 g/cm3

  20. Distance to the Sun • Aristotle was the first person to consider the problem. But Kepler was the first to obtain a precise measurement. • Recent measurements use radar bouncing off other planets to obtain more precise measurements.

  21. Size of the Sun • Aristarchus was the first to consider the size of the Sun. • The modern method involves the angle of the light rays. • 150 Earths would fit along the diameter of the Sun.

  22. The Mass of the Sun • Newton was the first person to find accurately the mass of the sun with his theory of gravitation. • 300,000X more massive than the Earth.

  23. The Density of the Sun • The density is simple calculation of the mass over the volume. • The density is only 40 percent higher than water suggesting a gaseous composition.

  24. The Layers of a Star • Core • Radiative Zone • Convective Zone • Photosphere • Chromosphere • Corona

  25. http://www.conceptdraw.com/samples/samplestour/Proton/Proton.gifhttp://www.conceptdraw.com/samples/samplestour/Proton/Proton.gif

  26. http://www.uniba.sk/~ago/pics/sun/1907anim.gif

  27. Sun Flare http://msowww.anu.edu.au/msovc/displays/images/sun-flare.jpg

  28. Sunspot Cycle http://www.hao.ucar.edu/public/education/sp/images/sunspotn.2.jpg

  29. Homework 7 • What is the luminosity of the Sun? What is the luminosity of a O type star? And what the luminosity of the K type star? How do they compare to the luminosity of the Sun? And how much heavier is the O than the K type star? • Two stars have magnitudes of 4 and 9 respectively. How much brighter is the star with magnitude 4 than the star with magnitude 9? If these two star were the same absolute magnitude (-4), how much further is the star with apparent magnitude of 9 than the star with the apparent magnitude of 4? • Page 391, CQ 3, 12 • Describe the different layers of the Sun via their respective temperatures and pressures.

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