1. Prior Knowledge Questions (Do these BEFORE using the Gizmo.)
How do the appearances of stars A, B, and C in the photo at left compare?
What are some ways the stars in the photo could be grouped or classified?

2. Chapter 29

3. “ Characteristics of Stars”
Objectives:
Describe how astronomers determine the composition & surface temperature of a star.
Explain why stars appear to move to an observer on the earth.
Name & describe the way astronomers measure the distance from the earth to the stars.
Explain the difference between absolute magnitude & apparent magnitude.

4. Star Composition All stars create light from Nuclear Fusion
Hydrogen + Hydrogen = Helium
Also may contain:
Carbon
Oxygen
Nitrogen
Calcium

5. How do we know what’s in a star?

14. 1 because of gravity 2 10,000,000 C 3 red supergiant 4 black holes 5 neutron star 6 red giant 7 planetary nebula 8 brown dwarf/black dwarf

15. Motion of Stars
1- Apparent Motion
circumpolar

18. 2- Actual Motion Rotate on their axis Revolve around another star
Move toward or away from the earth

21. Omega Centauri

22. Measuring Distance in Space
Use 1 Light-year = 9.5 trillion km
Remember the SUN is 8 light-minutes away
The next closest star is 4.2 light-years away
Polaris is 700 light-years away
Astronomers use PARALLAX to calculate distance in space

24. PARALLAX

25. Huge distances in space
Measured in parsecs (pc)
Parsec= 3.26 light years= x 1013 km

27. Stellar Magnitudes
Depends on the stars brightness & its distance from space
2 scales can be used
Apparent Magnitude: How it looks from Earth
Sun  Moon  Venus  Jupiter  Saturn  Sirius
Absolute Magnitude: Also called luminosity
How it would look if we were 10 parsecs away.
“BeetleJuice”  Rigel  Spica  Sirius

28. Apparent Magnitude

29. Absolute Magnitude