1 A) the Sun B) the Earth C) a small city D) a basketball 2 A) the shell of a planetary nebula expands and dissipates, leaving behind the dead core of a red giant. B) a massive star is destroyed in a supernova explosion, leaving behind a collapsed core made of neutrons. C) an interstellar cloud collapses and starts burning hydrogen. D) the helium fusion reactions in the core of a red giant experience a thermal runaway. 3 A) That the white dwarf would be emitting X-rays. B) That the person had made a mistake, as white dwarf stars cannot have less than 20 solar masses C) That the person did not know what they were talking about due to the Chandrasekhar limit. D) That such a white dwarf should have a red giant. 4 A) It is similar to gas pressure, but only affects protons. B) It is pressure caused by the electrostatic repulsion of positrons. C) The exclusion principle limits the number of electrons that can be put into a given volume, creating a pressure. D) It is a pressure caused when atoms bounce of each other in a gas. 5 A) Its radius decreases. B) Its density increases. C) It may exceed the Chandrasekhar limit and collapse. D) All of the above. 6 A) the Sun B) the Earth C) a small city D) a basketball 7 A) the shell of a planetary nebula expands and dissipates, leaving behind the dead core of a red giant. B) a massive star is destroyed in a supernova explosion, leaving behind a collapsed core made of neutrons. C) an interstellar cloud collapses and starts burning hydrogen. D) the helium fusion reactions in the core of a red giant experience a thermal runaway. 8 A) A rotating neutron star that emits radio waves in a narrow beam. B) A star whose luminosity changes as it swells and shrinks rhythmically. C) A star whose mass changes as it comes into contact with another star. D) A planetary nebula. 9 A) Yes; yes. B) Yes; no. C) No; yes D) No; no. 10 A) decreases; stays the same B) increases; stays the same C) stays the same; decreases D) stays the same; increases 11 A) Charged particles ripped off the surface of a neutron star spiral around its magnetic field lines. This acceleration causes them to radiate. B) The surface of a neutron star pulsates, throwing off waves of radiation. C) Pulsars radiate just like main-sequence stars. D) Pulsars do not radiate, because not even light can escape their strong gravity. 12 A) A white dwarf that no longer radiates light. B) The collapsed core of a very massive star whose gravitational force is so great that not even light can escape it. C) A very deep lunar crater. D) The burned-out remnant of a low-mass star. 13 A) They have seen tiny dark spots drift across the face of some distant stars. B) X-rays, perhaps from gas around a black hole, have been seen to disappear as a companion star eclipses the hole. C) They have seen a star suddenly disappear as it became a black hole. D) They have looked into a black hole with x-ray radar telescopes. 14 A) the distance from its center at which nuclear fusion ceases. B) the distance from its surface at which an orbiting companion will be broken apart. C) the maximum radius a neutron star can have before it collapses. D) the distance from body at which its escape velocity equals the speed of light. 15 A) 0.3 km. B) 3 km. C) 30 km D) 300 km
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