1. The Birth, Life, and Death of Stars
Stellar Evolution
The Birth, Life, and Death of Stars

2. The Universe Everything The Universe is 13.72 billion years old
All matter, space, and time
The Universe is billion years old

3. Cosmology
The study of the origin of the Universe

4. An average sized Star
About 4.5 billion years old
The Sun

5. What is a Solar System? A star and everything that revolves around it
Our Solar System is about ___ years old

6. A light-year A unit of distance, not time
The distance light travels in one year
6 Trillion miles

7. Distance to Sun
93 million miles
8.3 light-minutes

8. Proxima Centauri
The closest star to our sun
About 4 light-years away

9. Galaxies Stars are not evenly distributed in space.
They are in groups called Galaxies.

10. Types and Sizes of Galaxies
Types: Elliptical, Spiral, Irregular
Two sizes
Giant
Dwarf

11. The Milky Way Galaxy 100,000 light years across
Has Hundreds of billions of stars

12. Galaxy Clusters A Group of Galaxies Local Group 2 mly across
3 large & about 2 dozen dwarf
Andromeda 2.2 mly

13. Galaxy Superclusters A cluster of clusters
The Local (Virgo) Supercluster
100 clusters
100 mly across

14. Nearest Superclusters

15. Galaxy Superclusters

16. The Visible Universe

17. How big is the Universe?
The visible universe is 28 billion light years in diameter.
Why is that all that is visible?
The entire universe may be much bigger

18. How many Galaxies are there?
Hundreds of billions
Each has hundreds of billions of stars

20. Edwin Hubble 1920’s Discovered other galaxies
Discovered the Universe is expanding

21. The Expanding Universe
The Red Shift
Doppler effect

22. The Doppler Effect

23. The Big Bang
Tremendous explosion started the expansion of the universe
All of the matter and energy of the universe was contained at one point

25. Characteristics of Stars

26. Star Properties and Classification
Color
Temperature
Age
Apparent brightness
Distance from Earth

27. Star Brightness Apparent Magnitude Absolute Magnitude
How bright it looks from Earth
Absolute Magnitude
How much light it actually produces

28. Apparent Magnitude (Brightness)
Depends on actual brightness (luminosity) and distance away

29. Hertzsprung-Russell (H-R) Diagram
Compares a star’s Temperature (color) and its …
Absolute Magnitude (Brightness)

30. Hertzsprung-Russell (H-R) Diagram

31. Hertzsprung-Russell (H-R) Diagram
Things to Know
Color depends on temperature
Blue, White, Yellow, Orange, Red
The higher the Temperature the Brighter the Star (if in the main sequence)
White Dwarfs and Red Giants are exceptions
The Sun is in the main sequence (90% of stars)

32. Star Relative Size
The Sun is an averaged sized star

33. The Formation and Life Cycle of Stars
Stellar Evolution
The Formation and Life Cycle of Stars

34. Star Formation Originate in gas clouds in space called Nebula
Mostly Hydrogen
Gravity pulls it together

35. Nebula The contraction heats the gases
When it gets hot enough (27 million degrees) nuclear fusion starts

36. Nuclear Fusion Hydrogen nuclei are fused to make helium
The reaction produces heat energy, which causes more fusion

37. How big is a Nebula?
The Orion Nebula is about 2.5 light years across

40. Old Age When the hydrogen runs low Contractions make more heat
Causes nuclear fusion to make heavier elements
Expansion results in a Red Giant

41. White Dwarf
When energy is used, it shrinks to make a white dwarf

42. Supernovas Collapses abruptly then explodes Billions of times brighter
Creates heavier elements
Occurs only in very massive stars

43. After a Supernova
The outer layers are blasted into space to create a new nebula (starts the cycle over)
The core collapses to form a neutron star

44. Neutron Star Left over after a supernova
1 teaspoon weighs billions of tons

45. Black Holes
A star so dense, even light can not escape

47. Formation of Heavier Elements
Elements heavier than hydrogen are formed by nuclear fusion in Stars
Elements heavier then iron form during a Supernova

48. The End