1. Evolution of Stars

2. Hertzsprung –Russell Diagrams (H-R Diagrams)
A graph that shows the relationship of a star’s TEMPERATURE to its ABSOLUTE MAGNITUDE ( Its Brightness)
Main Sequence = Most stars ( 90 % of stars)
Our Sun is a main sequence star.

3. H-R Diagram

4. H-R Diagram

5. H-R Diagrams Bright, Hot , Blue stars are in the upper left.
Dim, Cool, Red stars are in the lower right.
Temperature in Kelvins is on the x-axis.
Brightness is on the y-axis. The sun =1 , for brightness.

6. Sizes Of Stars The SMALLEST are Black Holes
Neutron Stars ( 20 km, billion tons/cc)
White Dwarf
Yellows (medium…the SUN)
The LARGEST are the Red Supergiants

7. Black Holes

8. White Dwarf

9. Yellow & Orange Stars 1. Alpha Bootes 2. 36 light-yrs away.
x sun
4. Third brightest star in the sky.
Arcturaus is an orange giant

10. Red Giants
Red Giant

11. Red Super Giants Red Giants
It was found that Betelgeuse is one of the largest stars, almost the size of our whole solar system.

12. Betelgeuse : A Red Super Giant

13. Compare the Sizes of Stars

14. The Evolution of Stars:

15. Evolution of Stars Stars are created in nebulae.
Stars use up their nuclear fuel.
Stars change over time.
Stars “Age” like a living thing does.
Stars “die”

16. A Nebula

17. A Planetary Nebula: An Old Star

18. Stellar Evolution

19. Life of the Sun

20. Life of the Sun

21. Atoms are made in stars: YOU are star-stuff

22. Galaxies Our galaxy is the Milky Way.
It is part of a cluster or many galaxies known as the Local Group.

23. Galaxy Types
Elliptical = Shaped like a football.

24. Galaxies
Spiral = Spiral arms wind out from a center.

25. Galaxies
Irregular = many unusual shapes

26. Doppler Shift

27. Doppler Shift
In 1925, Edwin Hubble found that most galaxies are moving away from one another.
He used Doppler Shift ( p.694)=
Wavelengths of light moving away are stretched … They shift to Red ( Red Shift).
Galaxies moving closer to us shift to blue wavelengths of light.

28. SETI
SETI is a program in which scientists search for extraterrestrial intelligence. WEB