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ASTR-1020 Stellar Astronomy

ASTR-1020 Stellar Astronomy. Dr. J. Allyn Smith Day - 7. Course Announcements. Homework Chapter 3: Due Today Homework Chapter 4: Due Thur. Feb 10. Lab Next Week: Lenses & Telescopes Read Chapter 4 Homework Chapter 4: Due Thurs. Feb. 10 Exam 1 Thursday Feb. 10 - Chapters 1 - 4

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ASTR-1020 Stellar Astronomy

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  1. ASTR-1020Stellar Astronomy Dr. J. Allyn Smith Day - 7

  2. Course Announcements Homework Chapter 3: Due Today Homework Chapter 4: Due Thur. Feb 10. Lab Next Week: Lenses & Telescopes Read Chapter 4 Homework Chapter 4: Due Thurs. Feb. 10 Exam 1 Thursday Feb. 10 - Chapters 1 - 4 1st Quarter Observing nights: Thurs Feb. 10 & Mon. Feb. 14

  3. What can we learn by analyzing star light? • A star’s temperature

  4. If you pass white light through a prism, it separates into its component colors. long wavelengths IRROY G B I UV short wavelengths spectrum

  5. Photograph of a Star Cluster

  6. Spectra of a Star Cluster

  7. blue 4600 A 81 Filter Detector 81

  8. blue 4600 A 81 Filter Detector 85 green 5300 A 85

  9. blue 4600 A 81 Filter Detector 83 green 5300 A 85 yellow 5800 A 83

  10. blue 4600 A 81 Filter Detector 78 green 5300 A 85 yellow 5800 A 83 orange 6100 A 78

  11. blue 4600 A 81 Filter Detector 70 “Blackbody Curve” - a graph of an object’s energy output versus wavelength. The PEAK of this curve is related to the object’s temperature. UV IR green 5300 A 85 yellow 5800 A 83 orange 6100 A 78 red 6600 A 70

  12. Energy Output UV IR Wavelength “Blackbody Curve” - a graph of an object’s energy output versus wavelength. The WAVELENGTH that the PEAK of this curve occurs at tells us about the object’s TEMPERATURE and COLOR.

  13. Which object is hotter, an object that is emitting mainly red light or mainly blue light? increasing temperature

  14. increasing temperature Hot objects emit light that PEAKS at shortwavelengths (blue).Cool objects emit light that PEAKS at longwavelengths (red)

  15. Wien’s law Relates the temperature of an object to the wavelength of the peak in the black body curve. peak = (2.9 x 10-3) / Tkelvin (distance units in meters) The higher the object’s temperature, the shorter the wavelength of the peak for the light emitted by the object.

  16. Wien’s Law

  17. What is the wavelength of the PEAK of this “Blackbody” curve

  18. What color is our 5800K Sun? The Sun emits all wavelengths of electromagnetic radiation (light); however, the wavelengths of light it emits most intensely are in the green/yellow part of the spectrum.

  19. What color does the Sun appear? WHITE!! A star, like the Sun, which peaks in the middle of the visible part of the spectrum (green/yellow light) will appear WHITE to the Human eye because it is giving off nearly equal amounts of all the visible colors of light.

  20. Our Sun What if the Sun became hotter?

  21. Our Sun What if the Sun became cooler?

  22. A. Which object gives off the greatest amount of Blue light?B. Which object gives off the greatest amount of Red light?C. Which object would appear Red?D. Which object would have the lowest temperature? A B C

  23. Tutorial: Blackbody Radiation (pg. 57) Work with a partner! Read the instructions and questions carefully. Discuss the concepts and your answers with one another. Take time to understand it now!!!! Come to a consensus answer you both agree on. If you get stuck or are not sure of your answer, ask another group.

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