1. Classifying Stars A brief overview of how stars are formed and how to classify them Enter

2. Click the links below to navigate How a star is formed The mass of a star Life cycle of a star Stellar classification Types of stars- Part I Types of stars- Part II Hertzsprung-Russell Diagram A look at the H-R diagram Extra practice About the author Resources Quit

3. How is a Star Formed? Stars begin their lives as nebula Gravity then pulls together dust and gas from the nebula to form a protostar These clouds of dust and hydrogen gas then collapse under their own gravity The center of this cloud then becomes very hot and nuclear fusion occurs. This process releases so much energy that the star then shines with its own light. Quit

4. Stars are Different Sizes Stars have a life cycle that depends on the initial mass of the star. The more mass a star has, the faster it will burn. Low mass stars, or small stars, survive for billions of years. These small stars die quietly, and in their place, a small white dwarf is left behind. High mass stars, or large stars, survive for a few million years. These large stars die in supernova explosions, and in their place, a black hole is left behind. Quit

5. Summary: Life Cycle of a Star Quit Click on the picture above to watch a video from the history channel on the life cycle of a star!

6. Videos to Watch http://www1.teachertube.com/viewVideo.php ?video_id=73345http://www1.teachertube.com/viewVideo.php ?video_id=73345 http://www.youtube.com/watch?v=80eMTnn Ljhshttp://www.youtube.com/watch?v=80eMTnn Ljhs http://www.youtube.com/watch?v=HEheh1B H34Q

7. What is Stellar Classification? The classification of stars is based on the elements they absorb and their temperature, and are listed from hottest to coldest ClassTemperatureConventional ColorMass (The Sun=1) Radius (The Sun=1) Luminosity (The Sun=1) O30,100–60,000 Kblue60 M ☉M ☉ 15 R ☉R ☉ 1,400,000 L ☉L ☉ B10,100–30,000 Kblue white18 M ☉M ☉ 7 R ☉R ☉ 20,000 L ☉L ☉ A7,600–10,000 Kwhite3.1 M ☉M ☉ 2.1 R ☉R ☉ 80 L ☉L ☉ F6,100–7,500 Kyellowish white1.7 M ☉M ☉ 1.3 R ☉R ☉ 6 L ☉L ☉ G5,100–6,000 Kyellow1.1 M ☉M ☉ 1.1 R ☉R ☉ 1.2 L ☉L ☉ K3,600–5,000 Korange0.8 M ☉M ☉ 0.9 R ☉R ☉ 0.4 L ☉L ☉ M2,000–3,500 Kred0.3 M ☉M ☉ 0.4 R ☉R ☉ 0.04 L ☉L ☉ Quit

8. Types of Stars Type O Stars in Orion’s Belt Type B stars in the Pleiades open star cluster  Quit

9. Types of Stars (continued) Above: Type A Star- Vega Below: Type A Star-Sirius Type F Star- Procyon Type G Star- The Sun Type K Star- Arcturus Type M Star- Betelgeuse Quit

10. The Hertzsprung-Russell Diagram The H-R Diagram shows the relationship between absolute magnitude, luminosity, classification, and effective temperatures of stars. It is a graph that plots star color versus its luminosity. The H-R Diagram can be used to define different types of stars. It can also be used by scientists to measure how far away a star cluster is from the Earth. Quit

11. A Look at the H-R Diagram Quit

12. Star Cut-Outs For your assignment, print this slide, color the stars the appropriate color and cut out. Then, put the stars in order from coldest to hottest Betelgeuse 3,100 C 0.04 L Aldebaran 5,000 C 0.4 L The Sun 5,400 C 1.2 L Polaris 6,100 C 6 L Vega 10,000 C 80 L Spica 31,000 C 1,400,000 L Regulus 20,000 C 20,000 L Quit

13. Resources Life Cycle Video: Teacher Tube Images: Wikipedia- Nebulas Deep Space Photos Star Field Observatory Hubble Information Center H-R Diagram Quit