Star Life Cycle and Light Introduction video Life

Star Life Cycle and Light

Introduction video • Life Cycle of a Star • https: //app. discoveryeducation. com/ learn/videos/ad 707 d 0 b-b 7 c 4 -467 d 8 cc 2291 dda 0 d 9 e 61? has. Local. Host=true

1. 1 st Step: a. Stars form from nebulas (cloud of dust & gas)

2. 2 nd Step: a. As nebula contracts, a small star is formed called a protostar b. Eventually, the protostar will begin nuclear fusion (elements coming together) This is the birth of the star. c. Fusion is the process that creates light inside a star.

3. 3 rd Step: a. Star joins the main sequence 1. ) 90% of stars spend life here

Life Cycle of Stars 4. 4 th Step: a. What stars end up as depend on mass b. Low mass = red giant (massive star, a lot of fusion) c. High mass = supergiant (largest known star, burn out fast)

5. Death of Stars: a. Low and Medium mass stars • Planetary nebula – white dwarf: dense, faint star – black dwarf: dead star b. High mass stars • Supernova: exploding star • neutron star: remains of star • black hole: massive gravity absorbs everything near it

Low/medium mass stars High mass stars

Star Life Cycle Questions: 1. 2. 3. 4. 5. 6. 7. What is a nebula? How does a star form from a nebula? How is a protostar different from a star? What factors determine how long a star lives? What is the ultimate fate of our sun? What type of stars may become black holes? Describe the difference between a white dwarf and a black dwarf. 8. Describe the two alternatives for a supernova.

Light • The electromagnetic (EM) spectrum contains all of the different wavelengths of light. • Humans can only see a small portion of this, which is called visible light. (ROYGBIV) • Electromagnetic radiation (light) travels at the speed of light which is 299, 792, 458 meters/second. • The study of the properties of light that depend on wavelength is called spectroscopy.

Electromagnetic Spectrum

A Star’s Spectrum • A stars spectrum can tell us the stars chemical composition. From this we can figure out how big the star is and how old it is too. • The mass of a star can be determined by studying the color of the star.

C. Hertzsprung-Russell Diagram 1. Use - Classify stars & understand how stars change over time. 2. Basis - Plots temperature vs. luminosity

90% of all stars

Betelgeuse Sirius A SUN

H-R Diagram Questions: 1. Describe the size of stars in the H-R diagram (in comparison with the sun) in the upper right portion. 2. Describe the color of the stars in the upper right portion of the H-R diagram. 3. Describe the size of stars in the H-R diagram (in comparison with the sun) in the upper left portion. 4. Describe the color of the stars in the upper left portion of the H-R diagram. 5. Describe the size of stars in the H-R diagram (in comparison with the sun) in the lower right portion. 6. Describe the color of the stars in the lower right portion of the H-R diagram. 7. Describe the size of stars in the H-R diagram (in comparison with the sun) in the lower left portion. 8. Describe the color of the stars in the lower left portion of the H-R diagram. 9. Where in the H-R diagram would you find a star the same size and color as our sun? 10. What is the classification of the Sun? 11. How would you classify the brightest stars? (they may be in more than one star class. ) 12. Describe the difference between stars Sirius A and Betelgeuse. 13. Name the brightest star on your diagram. 14. Name the “coolest” star on your diagram. 15. Describe the movement of the Sun’s life cycle through the H-R diagram.