1. Stars

2. Stars
Star: a large celestial body that is composed of gas and that emits light.

3. Stars

4. States of Matter Temperature is a measure of energy Low energy = Solid
Medium energy = Liquid
High energy = Gas
Higher energy = Plasma
Plasma gives off light: lightning, flames, fluorescent light bulbs, northern lights, stars

5. Nebula Clouds of gases and dust Mostly hydrogen
Birthplace of stars and solar systems

7. Protostar Nebula collapses and pressure/temperature builds
Fusion Begins

8. How a Star Works Nuclear Fusion
At 15,000,000 oC hydrogen atoms (protons) fuse to form helium
A small amount of matter (solid stuff) is converted into energy
Einstein figured out how much energy:
E = mc2

9. Gravitational Collapse
Gas pressure and heat push outwards
Gravity pulls inward
Equilibrium
(everything equal or balanced)

10. New star clears out the nebula

12. Stars

13. The Hertzsprung-Russell diagram (HR Diagram)

15. Light Year A light year is the distance light travels in one year
Light travels at 186,000 miles each second
One light year is 5,869,713,600,000 (that’s almost 6 trillion miles!)
The sun is 8 light minutes away from Earth.
The next closest star to Earth is 4 light years away.

16. Dwarf Stars Variety of “colors”. Most common type.
Yellow Dwarf includes our own sun
Brown Dwarf – failed stars that never heated up enough to explode into a normal star
White Dwarf – collapsed stars that are slowly burning away the last of their fuel
Black Dwarf – non-luminous (no light) dead stars

17. Brown Dwarf “Almost” star
Bigger than a Jupiter-type planet, smaller than a true star
Hot core, but not star-hot
No (or little) fusion

18. Red Dwarf Small, cool star
Longest life span >10,000,000, (10 billion) years
Most numerous
Active fusion in core

20. Yellow Dwarf Our sun Active fusion in core
Lifetime about 10,000,000,000 years
Our sun is about 5,000,000,000 old

21. Red Giant
After a yellow dwarf burns up its fuel it cools and contracts
Temperature again rises and the star expands rapidly
Becomes a red giant
Our sun will be about the size of the Earth’s orbit (bye bye Mercury, Venus, Earth!)

23. Giants – Super Giants Giants Super Giants
1 thousand times brighter than the sun
200 times larger
Super Giants
10 million times brighter
Thousands of times larger

24. Binary Stars Two stars orbiting each other
Most common form of stars in the Milky Way
Jupiter 2 – 3 times more massive, we (don’t) exist in a binary star system

25. Binary White Dwarf System

26. Alpha Centauri – Proxima Centauri
Earth’s next closest neighbor star –
4 light years away

27. Planetary and Astronomical Scales

35. Supernova Massive stars Rapidly uses up hydrogen, fuses larger atoms
Requires energy instead of giving off energy
Stellar collapse causes rapid increase in pressure and temperature
Star explodes
Inner layers compressed into extremely tight ball of matter

37. Supernova
Visible
X-ray

38. Neutron Star Neutron Star (Super Massive…Heavy!!!)
Under collapse, protons and electrons combine to form neutrons.
10 km across

39. Black Hole Mass of core > 5 x Solar mass
Gravitational force so strong not even light can collapse
Center of most galaxies
Eats other stars
Not even compacted neutrons can support weight of very massive stars

40. Pulsars Neutron star that emits EM Radiation – radio – gamma
Pulse rotates rapidly causing the signal to fade in and out
Pulses occur as often as once per second

41. X-Ray Binaries
In close binary systems, material flows from normal star to Neutron Star or Black Hole.
X-rays emitted from disk of gas around Neutron Star/Black Hole.

42. Star Groups
Constellations: one of 88 regions into which the sky has been divided in order to describe the locations of celestial objects; a group of stars organized in a recognizable pattern.

43. Galaxy
Galaxy: a collection of stars, dust, and gas bound together by gravity.

44. Galaxies
You are here.

45. Spiral Galaxies
Spiral Galaxy: the most common type, where there is a nucleus of bright stars and a flattened arms that spiral around the nucleus. The arm consists of young stars, gas, and dust.

46. Milky Way = Our Galaxy Around 100,000,000,000 stars Spiral Galaxy
100,000 light years across

48. Elliptical Galaxies
Elliptical Galaxies: are extremely bright in the center and do not have spiral arms. Elliptical galaxies have few young stars and contain little dust and gas.

49. Irregular Galaxies
Irregular Galaxies: have low total masses and are fairly rich in dust and gas. (only a small percentage of total galaxies)

51. Quasars
Quasar: quasi-stellar radio source, a very luminous object that produces energy at a high rate. (very distant objects located in the center of galaxies)

54. The Big Bang Theory
Cosmology: the study of the origin, properties, processes, and evolution of the universe.

55. Hubble Space Telescope Research
The Hubble Telescope allowed researches to see that hundreds of galaxies have large red shifts; therefore, they are moving away from earth very fast.

56. The Universe is Expanding!

57. The Big Bang Theory
Big Bang Theory: the theory that all matter and energy in the universe was compressed into an extremely small volume that 13 to 15 billion years ago exploded and began expanding in all directions.

58. The Big Bang Theory
Cosmic Background Radiation: radiation uniformly detected from every direction in space, considered a remnant of the big bang.

59. Dark Energy / Dark Matter
Dark Matter: matter that does not give off light but that has gravity that we can detect. (23% of the universe)
Dark Energy: acts as a force that opposes gravity.

60. And the rest…