1. In a neutron star, the core is 7. What makes the Crab Nebula pulsar unusual A) made of compressed neutrons in contact among other pulsars? with each other. A) Its period is much less regular than other B) no longer rotating. pulsars. C) primarily iron and silicon. electrons and B) It is the fastest spinning known pulsar. protons packed so tightly they are in C) It is the oldest known pulsar. contact. D) It is a magnetar, with far more intense D) constantly expanding and contracting. magnetic fields than any other. 1. Two important properties of young neutron stars E) It is relatively bright in shorter wavelengths, are like visible and X-rays. A) extremely slow rotation and a strong 8. Who discovered the first four pulsars? magnetic field. A) Carl Sagan B) extremely rapid rotation and a weak B) Anthony Hewish magnetic field. C) Martin Schwartzschild C) no rotation and a weak magnetic field. D) Stephen Hawking D) no rotation and no magnetic field. E) Jocelyn Bell E) extremely rapid rotation and a strong 9. Pulsars magnetic field. A) generally form from 25 solar mass stars. 2. An object more massive than the Sun, but B) spin very rapidly when they're young. roughly the size of a city, is a C) emit radio radio in all directions. A) white dwarf. D) are the cause of gamma-ray bursts. B) brown dwarf. E) spin very slowly when they're young, and C) neutron star. gradually spin faster as they age. D) red dwarf. 10. In the Lighthouse Model, E) supernova remnant. A) the period of pulsation must speed up as the 3. The mass range for neutron stars is neutron star continues collapsing. A) .08 to .4 solar masses. B) all pulsars must have their poles pointed B) .4 to 3 solar masses. directly toward us. C) 1.4 to 3 solar masses. C) the period of pulsation slows down due to D) 3 to 8 solar masses. the drag of the remnant on its field. E) 6 to 11 solar masses. D) the star literally turns on and off like a 4. Which of these does not exist? lighthouse beacon. A) a million solar mass black hole E) if the beam sweeps across us, we will detect B) a 6 solar mass black hole a pulse of radiation. C) a 1.8 solar mass neutron star 11. Neutron stars do not have D) a 1.5 solar mass white dwarf A) strong magnetic fields. E) a 0.06 solar mass brown dwarf B) rotation periods comparable to the Sun's. 5. Most pulsars are observed only as ______C) sizes comparable to large cities. sources. D) masses greater than 1.4 solar masses. A) gamma-ray burster E) large surface gravities, compared to the Sun. B) x-ray 12. The supernova of 1054 produced C) radio A) an optically visible pulsar with a period of 33 D) visible lighthouse milliseconds. E) ultraviolet repeating B) the first known gamma-ray burster. 6. Neutron stars have C) no remaining trace, like most Type I A) no relation to pulsars. supernovae. B) weak or non-existent magnetic fields. D) a supernova remnant still visible to the C) monopolar fields that switch polarity every naked eye. rotation. E) the most famous black hole, Cygnus X-1. D) very strong bi-polar magnetic fields. 13. Three terrestrial-sized planets in orbits of a E) periods of days or weeks. fraction of an AU have been found near A) Cygnus X-1. B) a magnetar. C) a millisecond pulsar. D) a white dwarf. E) Supernova 1987A. 14. Many of the millisecond pulsars lie in ______, 21. A hypernova creates suggesting great stellar density. A) short-duration gamma-ray bursts. A) globular clusters B) a pulsar. B) giant molecular clouds C) a neutron star.. C) planetary nebulae D) a black hole. D) open clusters E) Both B and C are correct. E) emission nebulae 22. Which statement about gamma ray bursters is 15. X-ray bursters occur in binary systems, not correct? containing a A) In seconds, they radiate hundreds of times A) pair of white dwarfs. more energy than even supernovae do. B) white dwarf and a neutron star. B) They seem to be coming from far beyond our C) red giant and a neutron star. own Milky Way. D) pair of neutron stars. C) They are scaled up X-ray bursters, with more E) black hole and a main sequence star. massive objects involved. 16. Pulsars have a measured mass of D) Millisecond flickering implies they are tiny in A) less than 1.0 solar masses. size. B) about 1.4 solar masses. E) The beams may be bi-polar ejections from C) greater than 10 solar masses. the hypernova formation of black holes. D) 5.2 solar masses. 23. Which are the two most popular candidates for E) between 2 and 4 solar masses. gamma-ray bursters? 17. You would expect millisecond pulsars to be A) formation of uranium in the core of a A) part of a binary system. supergiant, and collisions of white dwarfs B) rotating slowly. B) mergers of two black holes, and merger of a C) isolated in space. neutron star and a white dwarf D) collapsing rapidly. C) hypernova making a black hole, and merger E) most common in open clusters. of two neutron stars D) collisions between a white dwarf and a 18. A proposed explanation for gamma-ray bursters giant, and merger of two neutron stars is E) hypernova making pulsars, and mergers of A) hypernova-making black holes and bi-polar two white dwarfs jets. B) coalescence of a neutron star binary. 24. Which statement about black holes is true? C) collisions between two white dwarfs. A) Their event horizon is a physical surface D) Both A and B are possible. boundary. E) All three are possible. B) Their escape velocity is greater than the speed of light. 19. What would happen if more mass was added to a C) Their main sequence mass was 5-10 solar 1.4 solar mass neutron star? masses. A) All of its protons and electrons would turn D) They form an event horizon at twice the into quarks. Schwartzschild radius. B) It could eventually become a black hole, via E) They form from 1.4 solar mass stars. a hypernova explosion. C) It would blow off mass as a gamma ray 25. The densely packed neutrons of a neutron star burster. cannot balance the inward pull of gravity if the D) It would erupt as a Type I supernova. total mass is E) It would grow larger, temporarily becoming a A) Chandrasekhar's limit of 1.4 solar masses. red giant again. B) greater than Schwartzschild's limit of 3 solar masses. 20. In a hypernova, a very energetic supernova C) less than 1.0 solar masses. creates a D) not at least 25 solar masses. A) set of planets to orbit their neutron star E) between 1.4 and 2.0 solar masses. host. B) black hole. 26. The Schwartzschild radius for a 12 solar mass C) white dwarf and its planetary nebula. star is D) very visible supernova remnant. A) 4 km E) millisecond pulsar. B) 15 km C) 36 km D) 100 km E) 3000 km 27. What explanation does general relativity provide 33. If the Sun were replaced by a one solar mass for gravity? black hole A) Gravity is the opposite of the A) life here would be unchanged. electromagnetic force. B) our clocks would all stop. B) Gravity is the result of curved spacetime. C) we would still orbit it in a period of one C) Gravity is directly proportional to the mass year. of the attracting body. D) we would immediately escape into deep D) Gravity is inversely proportion to the radius space, driven out by its radiation. of the body. E) all terrestrial planets would fall in E) Gravity can affect only massive particles, immediately. not massless photons. 34. What is Cygnus X-1? 28. An observer on a planet sees a spaceship A) a millisecond pulsar with three Earth-like approaching at 0.5c. A beam of light projected planets around it by the ship would be measured by this observer B) The brightest star in the constellation to travel at Cygnus. A) 0.25c C) the leading candidate for an observable B) 0.5c black hole binary system C) c D) the strongest x-ray eclipsing binary system in D) 1.5c the sky E) 2.5c E) the first gamma-ray burster to be spotted in 29. As a spaceship's velocity gets closer to the speed other wavelengths as well of light 35. A method for identifying a black hole is to A) its length will decrease and its clock will run A) search for their pulsar signal. more slowly. B) look for their effects on nearby companions. B) its length will decrease and its clock will run C) look for voids in the star fields. faster. D) search for radio waves from the accretion C) its length will increase and its clock will run disk. more slowly. E) locate a visible star that disappears when D) its length will increase and its clock will run the black hole passes in front of it. faster. 36. The largest known black holes E) None of these will happen. A) can be no more than 1.4 solar masses, 30. If light from a distant star passes close to a according to Chandrasekhar. massive body, the light beam will B) can be no bigger than the earth, like white A) bend towards the star due to gravity. dwarfs. B) continue moving in a straight line. C) lie in the cores of the most massive galaxies. C) accelerate due to gravity. D) can be no bigger than a small city, just like D) slow down. neutron stars. E) change color to a shorter wavelength. E) create the dark nebulae in the plane of the 31. What can we detect from matter that has Milky Way. crossed an event horizon? 37. Which of these is not an argument for Cygnus X-1 A) Gamma bursts. being a black hole? B) Visible light. A) It is the third strongest source of X-rays in C) Radio waves if the matter was traveling fast the sky. enough. B) Spectroscopic data suggests hot gas is D) X-rays if the matter was dense. flowing toward the X-ray source. E) Nothing. C) The X-rays from the compact source vary in 32. As a spaceship nears an event horizon, a clock as little as a millisecond. on the spaceship will be observed D) The mass of the visible star is greater than A) to run slowly. that of the X-ray source. B) to run faster. E) The mass of the X-ray source is about 10 C) to run backwards. solar masses. D) to run the same as one on Earth. E) to stop.