1. The Lifecycle of Stars

2. Measuring stars
Constellations are groups of stars that make a picture:
big dipper
Orion

3. Measuring distance
A Light year is the distance light travels in one Earth year
It is a measure of distance NOT speed!

4. Measuring brightness Magnitude is the brightness
Absolute magnitude is the actual brightness of a star
Apparent magnitude is how bright a star appears from Earth
Luminosity is the energy output from the surface of a star per second

5. All stars have nearly identical composition
Their differences in appearance is a result of their differences in surface temperatures
Blue 40,000K (~71,000oF)
White 10,000K
Yellow 7,000K
Orange 5,000K
Red 3,000K (~4,900oF)

7. Star size (mass) can also vary Our sun = 1 solar mass (2x1030kg)
Giants = are 8-30 solar masses
Super giants = solar masses
Also called “super massive”

8. H-R Diagram Plots data of mass, diameter, temperature, luminosity
Y-axis plots absolute magnitude
X-axis temperature (and spectral type)
Main sequence—90% of all stars fall w/i this band of stars on the diagram
These stars all have similar properties of structure and function

9. HR Diagram

11. Stellar Evolution Stars have a lifecycle Birth of the star is a nebula
Maturity is main sequence
Old age are red giants or super giants
Death are white dwarf, neutron star, black hole

13. Star Formation
All stars begin the same way but their evolution is determined by their mass

18. Black Hole Warping of space due to gravity