Transcript Chapter 29 Stellar Evolution

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?
Chapter 29
“ 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.
Star Composition
• All stars create light from Nuclear Fusion
– Hydrogen + Hydrogen = Helium
• Also may contain:
– Carbon
– Oxygen
– Nitrogen
– Calcium
How do we know what’s in a star?
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
Motion of Stars
1- Apparent Motion
– circumpolar
2- Actual Motion
– Rotate on their axis
– Revolve around another star
– Move toward or away from the earth
Omega Centauri
PARALLAX
Huge distances in space
• Measured in parsecs (pc)
• Parsec= 3.26 light years= 3.086 x 1013 km
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
Apparent Magnitude
Absolute Magnitude