1 / 22

Lab 07

Astronomy 105 Laboratory. Lab 07. Lab Quiz 7. Last week you determined the Earth’s orbital velocity using ______. Newton’s 2nd Law Wein’s Law the photoelectric effect Newton’s Law of Gravity the Doppler effect.

rianne
Download Presentation

Lab 07

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Astronomy 105 Laboratory Lab 07

  2. Lab Quiz 7

  3. Last week you determined the Earth’s orbital velocity using ______. • Newton’s 2nd Law • Wein’s Law • the photoelectric effect • Newton’s Law of Gravity • the Doppler effect

  4. If a star is moving away from Earth, the absorption lines in its spectrum will • have wavelengths shorter than those of an identical stationary star (blueshifted). • have wavelengths longer than those of an identical stationary star (redshifted). • be the same as those of an identical stationary star.

  5. In this week’s lab you will make a graph (HR diagram) comparing two stellar properties. Which property is plotted on the horizontal axis? • mass • size • temperature or spectral class • luminosity or absolute magnitude • eccentricity

  6. A star’s apparent magnitude is a measure of brightness as viewed from • the Earth. • 10 parsecs. • 100 parsecs. • 1000 parsecs. • 10 light-years

  7. A star’s absolute magnitude is a measure of brightness as viewed from • the Earth. • 10 parsecs. • 100 parsecs. • 1000 parsecs. • 10 light-years

  8. Lab 07 The Hr diagram

  9. Apparent Brightness of Stars • Stellar Luminosity -- Total amount of light energy emitted each second • Surface Area • Temperature • Distance from the Earth

  10. (2.512)5 = 100 (2.512)2 6.3 2.512 (2.512)3 16 Faintest stars visible to naked-eye Brightest stars in the night sky Measuring a Star’s Brightness Magnitude Scale 1 2 3 4 5 6 Brighter Dimmer Difference in apparent brightness between each magnitude step is 2.512

  11. C Apparent Magnitude 4.2 1 parsec (pc) = 3.26 ly Absolute Magnitude 5.0 6.0 0.0 B 3.3 2.0 D A 2.0 1.3 Sun -26.5 15 pc 10 pc 5 pc

  12. Magnitude • Stellar Brightness • Apparent Magnitude (mv) - Brightness from Earth • Absolute Magnitude (Mv) - Brightness from 10 pc Absolute magnitude depends only on a star’s luminosity

  13. Spectral Classification B

  14. A0 A1 A2 A3 A4 A5 A6 A7 A8 A9 F0 Sun (G2) 6,000 K Spectral Classification (a temperature scale) /Guy O B A F G K M h e ine irl iss e Hot 30,000 K Cool 3,500 K

  15. HR Diagram -10 -5 0 +5 +10 +15 The Sun M = +5 G2 Absolute Magnitude O B A F G K M Temperature Vertical Axis: Absolute Magnitude or Luminosity Horizontal Axis: Temperature (color, Kelvin or spectral type)

  16. HR Diagram

  17. Luminosity:Temperature E E A Hot Star The Sun R Rsun = Rhot star R 12,000 K 6,000 K Temperature 1 Lsun 16 Lsun Luminosity ?

  18. Luminosity:Size E E Big Star Small Star Rb Rs 6,000 K Msmall= 5 Mbig= 2 Big Star is more luminous than Small Star: Msmall– Mbig= 5 - 2 = 3 magnitudes Star 2 is more luminous than Star 1: Mv1 - Mv2 = 5 - 2 = 3 magnitudes Star 2 is 16 time brighter because it has 16 times the surface area. Star 2 is more luminous than Star 1: Mv1 - Mv2 = 5 - 2 = 3 magnitudes Star 2 is 16 time brighter because it has 16 times the surface area Big Star is 16 times brighter. Why? Big Star has 16 times the surface area! Surface Area = 4r2

  19. The Sun’s Spectral and Luminosity Class:G2 V

  20. The End

  21. Luminosity:Size E E Big Star Small Star R2 R1 6,000 K M1 = 5 M2 = 2 Big Star is more luminous than Small Star: Star 2 is more luminous than Star 1: Mv1 - Mv2 = 5 - 2 = 3 magnitudes Star 2 is 16 time brighter because it has 16 times the surface area. Star 2 is more luminous than Star 1: Mv1 - Mv2 = 5 - 2 = 3 magnitudes Star 2 is 16 time brighter because it has 16 times the surface area M1 – M2 = 5 - 2 = 3 magnitudes Big Star is 16 times brighter. Why? Big Star has 16 times the surface area! Surface Area = 4r2

More Related