1. Study Guide Answers Stars and Galaxies SUBTITLE

2. Study Guide Answers #1 A telescope is an instrument that helps to focus light to allow far off objects to be seen. #2 Telescopes are used by astronomers to study objects in space. #3 A reflecting telescope uses curved mirrors, and the refracting uses convex lens to focus light.

3. Study Guide Answers #4 Hubble is a reflecting telescope. #5 Electromagnetic radiation detected by telescopes include visible, radio, infrared, and x-rays. #6 All matter was contained within a singularity. It began to expand outward eventually forming all objects in the Universe. It helps to explain how the Universe was formed.

4. Study Guide Answers #7. A light year is the distance light travels in one year. It is used to describe distant objects like stars and galaxies. #8 A spectroscope is an instrument that breaks light into parts for analysis. It helps scientists identify elements found within stars and other objects in space. #9 Dark matter is matter that cannot be seen in space, but scientists believe it provides the gravity to hold galaxies together.

5. Study Guide Answers #10. A galaxy is a grouping of stars held together by gravity. #11 Three types of galaxies: Spiral, Elliptical, Irregular #12 Our galaxy is the Milky Way which is spiral.

6. Study Guide Answers #13 Older Stars reside primarily in this galaxy – E Contains stars, gas, and dust – S, E, I Younger and older stars are found - S, I Has arms that spin around central section – S Can be circular to oval – E Has no definite shape – I Held together by gravity – S, E, I

7. Study Guide Answers SpiralEllipticalIrregular

8. Study Guide Answers #15 The Sun is our closest star. #16 Stars form out of gas and dust in a nebula, called protostar at the beginning. #17 Our sun is in Main Sequence. #18 After main sequence, our star will become a red giant and end its life as a white dwarf.

9. Study Guide Answers #19 Star burns hydrogen together to produce helium. In later stages, helium is fused to make larger elements. #20 A planetary nebula contains leftover pieces of stars. #21 A supernova is when a high mass star explodes, happens after Super Giant stage.

10. Study Guide Answers #22: Type I supernova: star accumulates matter from a nearby neighbor until a runaway nuclear reaction ignites. Type II supernova: star runs out of nuclear fuel and collapses under its own gravity #23 A star can’t fuse iron because it would take more energy to fuse it than the star would be able to emit.

11. Study Guide Answers #24 A neutron star is a a very heavy star that contains all the matter of a supergiant squeezed into a much smaller volume. (High mass stars only) #25 A pulsar develops when a neutron star spins rapidly due to a high amount of magnetic energy. #26. The spinning action of neutron star causes some to collapse and gravity pulls nearby objects and light into center.

12. Study Guide Answers #27. What is a brown dwarf. A star that did not have enough energy to begin nuclear fusion. It is between the size of a planet and a small star. #28. All stars go through nebula, protostar, main sequence. Small mass – Red Giant, Planetary Nebula, White Dwarf, Black Dwarf Large mass – Supergiant, Supernova, Neutron Star, Pulsar, Black Dwarf

13. Study Guide Answers #29 Hottest stars are blue, coldest are red. #30 Our Sun is yellow, average temperature. #31 First magnitude stars are brighter than 6 th magnitude. #32. Magnitude measures luminosity or brightness. #33. Apparent magnitude is brightness as we view it. Absolute magnitude is the scientific measurement of brightness.

14. Study Guide Answers #34. A parallax is a method used to measure the distance of stars closer to Earth. #35. Hertzsprung Russell Diagram (HR) is a graph that helps to classify stars. #36. Temperature is on x axis of HR Diagram. #37. Luminosity or brightness is on y axis of HR Diagram.

15. Study Guide Answers #38. Distance from Earth and Brightness is used to determine luminosity. #39. Main sequence are found on diagonal band that goes from top left to bottom right of HR Diagram. #40. White dwarfs are found in the bottom left of the HR Diagram.

16. Study Guide Answers 41. Red giants are found in the top right corner of the HR Diagram. 42. Most stars are in main sequence since this is the longest stage of a star’s life.

17. Study Guide Answers 43. Which star is not in Main Sequence: Betelgeuse, Sun, Zeta Eridani, or Procyon? Answer: Betelgeuse

18. Study Guide Answers 44. Which star is brighter: Capella or Antares? Antares – higher on graph, so brighter

19. Study Guide Answers 45. Which star is hotter: Sirius B or Alpha Centauri A? Answer: Sirius B since it is further left (temperature)

20. Study Guide Answers 46.Using both brightness and temperature, describe our Sun. Answer: Average temperature with a little less than average brightness. (Main Sequence)

21. Study Guide Answers 47. What color star is North Star? Answer: Yellow 48. What color is Barnard’s Star? Answer: Red

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