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Unformatted text preview: 31. Suppose that a helium balloon is moved from a warm room to the cold outdoors. Based on the ideal gas law, what will happen to the balloon and why? 32. What is the fundamental quantity that varies along the spectral sequence (O B A F G K M)? What are the principal differences between the spectra of O and M stars? What type of star is the Sun? 33. Sketch an H-R diagram. Label the axes (give the physical quantity corresponding to the axis; you do not need to put numbers on the axis). Use arrows to indicate in which direction the quantities increase. Sketch and label the locations of the main sequence, red giants, supergiants, and white dwarfs. 34. Explain why a red giant star has a much higher luminosity than a main sequence star with the same surface temperature. 35. Where do we find low-mass stars on the main sequence? High-mass stars? 36. Compare the lifetime of a red dwarf and a blue supergiant. What accounts for this difference in lifetime? A105, Prof. Cohn, First Semester 2012-13 3 37. In what types of regions do stars form? 38. How is the energy lost by radiation from the surface of a protostar replaced? 39. Why can more be learned about protostars by observing them in infrared rather than visible light? 40. Describe why a reflection nebula has a bluish color and why a star that lies behind a reflection nebula appears to be redder than its true color. 41. Explain why Earth’s sky is blue....
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- Fall '12
- apparent brightness, Prof. Cohn, different apparent brightness