Ch. 16/17 Test

1. the first stage in the life cycle of a star
3. measures the amount of light reaching Earth
4. a huge cloud of dust and gas from which stars form
7. the total amount of light given off by a star
8. a stable star in the main category in the H-R diagram
11. the explosion of a very large star
12. an enormous hot ball of gas held together by gravity which produces energy through nuclear fusion reactions in its core
13. a large star with low temperature and high brightness
14. very large, bright star that may be blue or red, depending on its temperature

1. the expanding outer shell of a sunlike star. This matter is blown away as the core shrinks to become a white dwarf
2. theory that the universe began as a huge explosion 10 billion to 20 billion years ago
3. a system of two stars orbiting each other that are gravitationally tied together
5. a small star with a high temperature and low brightness
6. reactions which combine light elements such as hydrogen into heavier elements such as helium, releasing energy
8. the spiral galaxy to which our solar system belongs
9. a method of studying an object by examining the visible light and other electromagnetic waves it creates
10. the distance light travels through space in one year
15. a group of stars, dust, gas, and other objects held together by gravitational forces