Chapter 17: 1. What two factors determine how bright a star appears to be in the sky? 9. The star Antares has an apparent magnitude of 1.0, whereas the star Procyon has an apparent magnitude of 0.4. Which star appears brighter in the sky? 10. Based on their colors, which of the following stars is hottest? Which is coolest? Archenar (blue), Betelgeuse (red), Capella (yellow). 11. Order the seven basic spectral types from hottest to coldest 21. Appendix I Iists some of the nearest stars. Are most of these stars hotter or cooler than the Sun? Do any of them emit more energy than the Sun? If so, which ones? 22. Appendix J lists the stars that appear brightest in our sky. Are most of these hotter or cooler than the Sun? Can you suggest a reason for the difference between this answer and the answer to the previous question? (Hint: Look at the luminosities.) Is there any tendency for a correlation between temperature and luminosity? Are there exceptions to the correlation? Chapter 18: 6. Sketch an H–R diagram. Label the axes. Show where cool supergiants, white dwarfs, the Sun, and main sequence stars are found. 23. An astronomer discovers a type-M star with a large luminosity. How is this possible? What kind of star is it? Chapter 19: 1. Explain how parallax measurements can be used to determine distances to stars. Why can we not make accurate measurements of parallax beyond a certain distance? 17. Which of the following can you determine about a star without knowing its distance, and which can you not determine: radial velocity, temperature, apparent brightness, or luminosity?