Universe Eighth Edition

1. Roger A. Freedman • William J. Kaufmann III Universe Eighth Edition CHAPTER 16 Our Star, the Sun

5. Stars in different stages of their evolution may generate energy using different nuclear reactions. These reactions can occur in the core or in a layer around the core. At the present, the energy of the Sun is generated • in its central core by fission of heavy nuclei. • from gravitational energy as the Sun slowly shrinks. • in its core by radioactive decay of uranium. • in the central core by fusion of helium nuclei and in an outer shell by fusion of hydrogen nuclei. • in its central core by fusion of hydrogen nuclei. Q16.1

6. Stars in different stages of their evolution may generate energy using different nuclear reactions. These reactions can occur in the core or in a layer around the core. At the present, the energy of the Sun is generated • in its central core by fission of heavy nuclei. • from gravitational energy as the Sun slowly shrinks. • in its core by radioactive decay of uranium. • in the central core by fusion of helium nuclei and in an outer shell by fusion of hydrogen nuclei. • in its central core by fusion of hydrogen nuclei. A16.1

15. The surface layers of the Sun are very massive. What stops the Sun from collapsing under its own weight? • The strong nuclear repulsion between the atoms of these layers. • Neutrinos exert a strong outward pressure, holding the layers up. • The magnetic field exerts a strong force. • The pressure of the very high-temperature gas within the Sun supports the outer layers. • The interior of the Sun is under such high pressure that it is solid. Q16.7

16. The surface layers of the Sun are very massive. What stops the Sun from collapsing under its own weight? • The strong nuclear repulsion between the atoms of these layers. • Neutrinos exert a strong outward pressure, holding the layers up. • The magnetic field exerts a strong force. • The pressure of the very high-temperature gas within the Sun supports the outer layers. • The interior of the Sun is under such high pressure that it is solid. A16.7

24. This photo shows solar granulation. The darker areas are regions where the gas is • hotter. • cooler. • Doppler shifted. • moving laterally. • less dense. Q16.9

25. This photo shows solar granulation. The darker areas are regions where the gas is • hotter. • cooler. • Doppler shifted. • moving laterally. • less dense. A16.9

30. The dark regions on this photo of the Sun are • the corona. • solar granules. • Zeeman effects. • sunspots. • prominences. Q16.11

31. The dark regions on this photo of the Sun are • the corona. • solar granules. • Zeeman effects. • sunspots. • prominences. A16.11

43. Stars in different stages of their evolution may generate energy using different nuclear reactions. These reactions can occur in the core or in a layer around the core. At the present, the energy of the Sun is generated • in its central core by fission of heavy nuclei. • from gravitational energy as the Sun slowly shrinks. • in its core by radioactive decay of uranium. • in the central core by fusion of helium nuclei and in an outer shell by fusion of hydrogen nuclei. • in its central core by fusion of hydrogen nuclei. A16.1

44. The “fuel” of the Sun is ______, and the main products of the nuclear reactions include ______. • hydrogen / helium, neutrinos, and gamma rays • helium / only neutrinos and gamma rays • hydrogen / neutrinos and microwaves • helium / neutrinos and microwaves • hydrogen / only neutrinos. Q16.2