Stars Study Guide Key

Stars Study Guide KEY DO NOT WRITE ON THIS PAGE! Use this KEY to check your study guide for accuracy. Answers do not need to be word-for-word the same(but important facts/details should not be missing! Goal 1: Diagram the life cycle of stars. Explain how the cycle for low-mass stars differs from that of highmass stars. 1. What role does gravity play in the birth of a star? Gravity pulls the gas and dust in a nebula together. When enough heat and pressure builds up, nuclear fusion starts and the star is born. 2. Describe the life cycle of a low/medium mass star. (Tell the steps in the life cycle.) The steps are: nebula, mature star, red giant, planetary nebula, white dwarf, black dwarf. 3. Describe the life cycle of a high mass star. (Tell the steps in the life cycle.) The steps are: nebula, mature star, red SUPER giant, then supernova. Then it can become a nebula again or either a neutron star or a black hole. 4. Tell the following about a “mature” star: What reaction is happening at its core? Nuclear fusion What two things is it “giving off”? Light and heat 5. Tell how low mass stars are similar to high mass stars. Low and high mass stars all begin in a nebula, are made of matter, burn due to nuclear fusion, and will eventually die. Once they begin to run out of fuel, they all go through “giant” phases. 6. Tell how low mass stars are different from high mass stars. Low mass stars will not go “supernova” and don’t become black holes or neutron stars. They do not burn with a white or blue color. They have less gravity. Low mass stars can become white/black dwarves; high mass stars will not. *7. Which stars live the longest, high-mass or low-mass? Low Mass Stars live longer. Why? They have less self-gravity which means they burn through their fuel slower. 8. What will happen to our star, the Sun, at the end of its life? The sun will expand in the Red Giant phase, then will release its outer layers to form a planetary nebula. It will become a white dwarf and then over time cool down to become a black dwarf. It will NOT go supernova or become a black hole. Goal 2: Explain how scientists use light to analyze stars; Goal 3: Describe our sun in terms of age, temperature, size, color, and chemical composition. 9. How do scientists use a star’s black line spectrum to find out what it is made of? They use the pattern of lines to figure out what elements are present in the star. (They can do this because each element has its own pattern of lines.) 10. What are most stars made of? Hydrogen, helium, and a small amount of other elements 11. What is “apparent magnitude” and what does it depend on? It is how bright a star appears to our eyes as seen here on Earth. It depends on how far away the star is and how bright the star actually is (it’s absolute magnitude) 12. What is “absolute magnitude” and what does it depend on? It is how bright the star actually is (compared to our sun or other stars). It depends on the star’s size/mass and temperature. 13. How do white dwarfs and neutron stars compare in size to our Sun? They are both smaller than our Sun. White dwarfs are “planet size”; neutron stars are about 20 km in diameter. 14. Describe what a low-mass star’s temperature and color range would be. Low mass stars have less self-gravity which means they burn at lower temperatures and produce yelloworange-red colors. 15. Describe what a high-mass star’s temperature and color range would be. High mass stars have more self-gravity which causes them to burn at a higher temperature and to produce white-blue colors. 16. Our sun has the following: chemical composition: Mostly hydrogen & helium color: yellow size: medium temperature: ~ 6000°C 17. Draw five constellations using the correct number of stars and correct placement. Tell the “nickname: of each constellation. Orion Cygnus Cassiopeia Nickname: The Hunter # of Stars: 7 Drawing: Nicknames: The Swan and the Northern Cross # of Stars: 8 Drawing: Nickname: The Queen # of Stars: 5 Drawing: Ursa Major Scorpius Nickname: The Great Bear # of Stars: 15 Drawing: Nickname: The Scorpion # of Stars: 13 Drawing: Goal 5: Define and differentiate the types of galaxies. 18. Identify and describe the three main types of galaxies. Spiral = central disk with arms that spiral outward, can be “bar” or “pinwheel”; Ellipse = round/flattened ball of stars; Irregular = does not fit the other two patterns; does not have a regular shape. 19. Tell what type of galaxy the Milky Way is. Scientists think it’s a spiral; it is probably a bar spiral, but may be a pinwheel.