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ASTR 1102-002 2008 Fall Semester

ASTR 1102-002 2008 Fall Semester. Joel E. Tohline, Alumni Professor Office: 247 Nicholson Hall [Slides from Lecture02]. Course Syllabus ( corrected Final Exam time!). Evaluation of Coursework. Corrected final exam time!. Chapter 17: The Nature of Stars. Describe Population (of stars).

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ASTR 1102-002 2008 Fall Semester

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  1. ASTR 1102-0022008 Fall Semester Joel E. Tohline, Alumni Professor Office: 247 Nicholson Hall [Slides from Lecture02]

  2. Course Syllabus(corrected Final Exam time!)

  3. Evaluation of Coursework Corrected final exam time!

  4. Chapter 17: The Nature of Stars

  5. Describe Population (of stars) • Location • Coordinate position • Distance • Motion • Across the photo/sky • Toward/away from us • Intrinsic properties • Mass • Color • Brightness • Age

  6. Describe Population (of fans) • Location • Coordinate position • Distance • Motion • Across the photo/sky • Toward/away from us • Intrinsic properties • Mass (weight) • Color (clothes) • Brightness (?) • Age

  7. Location – Determine exact location of every fan! • Coordinate position • Distance

  8. Location – Determine exact location of every fan! • Coordinate position (x-y coordinate on photo) • Distance (distance from photographic lens)

  9. Location – Determine exact location of every fan • Coordinate position (x-y coordinate on photo) straightforward • Distance (distance from photographic lens)

  10. Location – Determine exact location of every fan • Coordinate position (x-y coordinate on photo) • Distance (distance from photographic lens) not so straightforward!

  11. e.g., Google Earth • Location – or … using GPS system … • Coordinate position (latitude & longitude) • Distance (altitude above sea level)

  12. Google Earth

  13. Location – Determine exact location of every star! • Coordinate position • Distance

  14. Location – Determine exact location of every star! • Coordinate position (“declination” & “right ascension”) • Distance (from Earth)

  15. Straightforward: Analogous to “latitude” & “longitude”; e.g., Google Sky Textbook ‘Box 2-1’ pp. 30-31 • Location – Determine exact location of every star! • Coordinate position (“declination” & “right ascension”) • Distance (from Earth)

  16. Google Sky

  17. Location – Determine exact location of every star! • Coordinate position (“declination” & “right ascension”) • Distance (from Earth) not so straightforward!

  18. Determining Distances to Astronomical Objects • Not at all straightforward! • Only direct method is “Stellar Parallax” • See textbook discussion associated with Figs. 17-1 and 17-2 • Other indirect methods will be discussed later

  19. Parallax

  20. Stellar Parallax

  21. Individual Stars… • Location in Space • Coordinate (angular) position on the sky • Distance from Earth • Motion through Space • Motion across the sky (“proper” motion) • Motion toward/away from us (radial velocity) • Intrinsic properties • Brightness (luminosity/magnitude) • Color (surface temperature) • Mass • Age

  22. Individual Stars… • Location in Space • Coordinate (angular) position on the sky • Distance from Earth • Motion through Space • Motion across the sky (“proper” motion) • Motion toward/away from us (radial velocity) • Intrinsic properties • Brightness (luminosity/magnitude) • Color (surface temperature) • Mass • Age

  23. Motion • Across the photo/sky • Toward/away from us • Location • Coordinate position • Distance

  24. Motion • Across the photo/sky • Toward/away from us • Location • Coordinate position • Distance

  25. Motion • Across the photo/sky • Toward/away from us • Location • Coordinate position • Distance

  26. Which object in this photo is moving?

  27. Motion Across the Sky(“proper” motion) http://www.psi.edu/~esquerdo/jim/astfov.gif

  28. Motion • Across the photo/sky • Toward/away from us • Location • Coordinate position • Distance

  29. Determining Motion of Astronomical Objects toward/away • Surprisingly straightforward! • Doppler effect • See textbook discussion in Chapter 5, §5-9

  30. Doppler Effect (§5-9) • The measured frequency (wavelength) of light changes if the light source is moving toward or away from you • Light is “blue-shifted” if the object is moving toward you • Light is “red-shifted” if the object is moving away from you • Direct analogy with the behavior of sound waves

  31. Individual Stars… • Location in Space • Coordinate (angular) position on the sky • Distance from Earth • Motion through Space • Motion across the sky (“proper” motion) • Motion toward/away from us (radial velocity) • Intrinsic properties • Brightness (luminosity/magnitude) • Color (surface temperature) • Mass • Age

  32. Prominent and Obscured Objects

  33. Prominent and Obscured Objects

  34. NOTE: Transient Events (in time) also occur

  35. NOTE: Transient Events (in time) also occur

  36. NOTE: Transient Events (in time) also occur

  37. NOTE: Transient Events (in time) also occur

  38. NOTE: Transient Events (in time) also occur

  39. Individual Stars… • Location in Space • Coordinate (angular) position on the sky • Distance from Earth • Motion through Space • Motion across the sky (“proper” motion) • Motion toward/away from us (radial velocity) • Intrinsic properties • Brightness (luminosity/magnitude) • Color (surface temperature) • Mass • Age

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