1) If the Sun were replaced by a one solar mass black hole 1) A) life here would be unchanged. B) we would still orbit it in a period of one year. C) all terrestrial planets would fall in immediately. D) our clocks would all stop. E) we would immediately escape into deep space, driven out by its radiation. 2) What can we detect from matter that has crossed an event horizon? 2) A) Radio waves if the matter was traveling fast enough B) Visible light C) Gamma bursts D) X-rays if the matter was dense E) Nothing 3) The radio source is located in a place consistent with the center of our Galaxy. 3) A) Sgr A* B) 3C 273 C) M-8, the Lagoon Nebula D) Cygnus X-1 E) 47 Tucanae 4) What compelling evidence links pulsars to neutron stars? 4) A) Pulsars are known to evolve into neutron stars. B) Both pulsars and neutron stars have been discovered near the Sun. C) Pulsars are always found in binary systems with neutron stars. D) Only a small, very dense source could rotate that rapidly without flying apart. E) Both pulsars and neutron stars can be found in globular star clusters. 5) Beyond the formation of iron, nuclear energy can be produced only by 5) A) gravity. B) fission of heavy nuclei back toward lighter ones. C) ionization of the radioactive nuclei. D) the dark force. E) fusion of still heavier elements. 6) The densely packed neutrons of a neutron star cannot balance the inward pull of gravity if the total mass is 6) A) less than 1.0 solar masses. B) greater than 25 solar masses. C) greater than Schwartzschild's limit of 3 solar masses. D) between 1.4 and 2.0 solar masses. E) Chandrasekhar's limit of 1.4 solar masses. 7) The alpha process tends to produce chiefly 7) A) even numbered elements. B) only carbon. - 1 -
C) stable elements. D) odd numbered elements. E) only radioactive elements. 8) All RR Lyrae stars have about the same 8) A) period of six hours. B) distance of 32 light years. C) luminosity of about 100 Suns. D) galactic location and speed. E) locations in the centers of globular star clusters. 9) Which of the following are most massive and luminous? 9) A) brown dwarfs B) white dwarfs C) T-Tauri variables D) RR Lyrae variables E) Cepheid variables 10) Which of the following are attracted by gravity? 10) A) any object with mass B) neutrinos C) electromagnetic radiation D) antimatter E) all of the above 11) Based on star counts, 100 years ago most astronomers thought: 11) A) we lay near the center of a disk about 10 kpc wide and 2 kpc thick. B) we lay near the edge of the only galaxy in the universe. C) we lay in a spiral arm of the largest galaxy in the universe. D) we were not a part of any structure larger than the known solar system. E) we lay about 30,000 ly out from the center of the Galaxy. 12) In neutronization of the core, a proton and an electron make a neutron and a 12) A) positron. B) neutrino. C) pion. D) antineutron. E) muon. 13) What observations suggest the mass of the Galaxy goes much farther out than its visible disc? 13) A) x-ray images of other galaxies' discs from Chandra B) infrared observations of distant brown dwarfs C) 21 cm maps of the spiral arms D) the rotation curve of the outermost portions of the disc E) the orbits of the open clusters in the disc 14) Why does neutron capture work? 14) A) Photodisintegration makes many alpha particles, available for capture by nuclei. - 2 -
B) Neutronization captures all the protons and electrons. C) Neutrinos, because of their low mass and high speed, easily penetrate nuclei. D) Neutrons have no repulsive barrier to overcome in combining with positively charged nuclei. E) Single protons have little repulsion to heavy nuclei and easily fuse with them. 15) What two observations allow us to calculate the Galaxy's mass? 15) A) the Sun's mass and its age B) the Sun's orbital velocity and its distance from the Galactic Center C) the Sun's composition and luminosity D) the Sun's age and period of the Galactic Year E) the Sun's mass and velocity in orbit of the Galactic Center 16) A method for identifying a black hole is to 16) A) search for their pulsar signal. B) locate a visible star that disappears when the black hole passes in front of it. C) search for radio waves from the accretion disk. D) look for their effects on nearby companions. E) look for voids in the star fields. 17) Which two classes of objects were critical to the Shapley-Curtiss Debate of 1920? 17) A) white dwarfs and red giants B) open clusters and emission nebulae C) emission nebulae and spiral nebulae D) globular clusters and spiral nebulae E) planetary nebulae and white dwarfs 18) For a white dwarf to explode entirely as a Type I supernova, it's mass must be 18) A) 20 solar masses, the Hubble Limit. B) 3 solar masses, the Schwartzschild Limit. C) 100 solar masses, the most massive known stars. D) 1.4 solar masses, the Chandrasekhar Limit. E) at least 0.08 solar masses. 19) What is stellar nucleosynthesis? 19) A) The formation of white dwarfs, neutron stars, and black holes from stars. B) The formation of heavier elements inside stars. C) The formation of stars from a nucleus of contracting material. D) The formation of planetary nebulae by red giants. E) The process by which stars form interstellar dust. 20) Almost half of all known millisecond pulsars are found in what type of object? 20) A) giant molecular clouds B) emission nebulae C) globular clusters D) open clusters E) supernova remnants - 3 -
21) Which is the correct description for the Sun's location in the Galaxy? 21) A) at the very outer edge of the disk, but in the galactic plane B) at the outer edge of the bulge, but along the galactic equator C) about 30,000 ly out in the halo D) in the disk, and about half way out from the center E) in the disk in the inner region of the Sagittarius Arm 22) Pulsars 22) A) spin very slowly when they're young, and gradually spin faster as they age. B) generally form from 25 solar mass stars. C) are the cause of gamma-ray bursts. D) spin very rapidly when they're young. E) emit radio radio in all directions. 23) The largest known black holes 23) A) can be no bigger than the earth, like white dwarfs. B) can be no bigger than a small city, just like neutron stars. C) can be no more than 1.4 solar masses, according to Chandrasekhar. D) lie in the cores of the most massive galaxies. E) create the dark nebulae in the plane of the Milky Way. 24) A proposed explanation for gamma-ray bursters is 24) A) coalescence of a neutron star binary. B) hypernova-making black holes and bi-polar jets. C) collisions between two white dwarfs. D) Both A and B are possible. E) All three are possible. 25) Both RR Lyrae and Cepheid variable stars are stars that, when on the main sequence, were considered to be 25) A) high mass. B) zero-age main sequence. C) blue stragglers. D) intermediate mass. E) low mass. 26) Which of these is the likely progenitor of a type I supernova? 26) A) a mass-transfer binary, with the white dwarf already at 1.3 solar masses B) an evolved red giant which is just starting to make silicon in its core C) an evolved blue supergiant that is about to experience the helium flash D) a contact binary, with the neutron star at 2.3 solar masses E) a helium-neon white dwarf 27) The mass range for neutron stars is 27) A).08 to.4 solar masses. B).4 to 3 solar masses. C) 1.4 to 3 solar masses. - 4 -
D) 3 to 8 solar masses. E) 6 to 11 solar masses. 28) Which of these objects have not been found in the Galactic Halo? 28) A) globular clusters B) planetary nebulae C) emission nebulae D) Population II stars E) RR Lyrae variables 29) What is one of the differences between Cepheids and RR Lyrae variables? 29) A) All Cepheids have the same brightness, but RR Lyrae stars vary greatly in luminosity. B) Cepheids are giants, but RR Lyrae stars are still on the main sequence. C) The RR Lyrae stars have much shorter periods than Cepheids. D) The pulsations of RR Lyrae stars are much less regular than those of Cepheids. E) The period-luminosity relation holds only for RR Lyrae stars. 30) Which of these is NOT true about supernovae? 30) A) The two types are both closely related to evolution of white dwarfs. B) Neutronization is vital in understanding type II core collapse. C) Type II involves formation of iron in the core. D) The one in 1987 in the Large Magellanic Cloud was of type II. E) Type I involves carbon detonation. 31) What explanation does general relativity provide for gravity? 31) A) Gravity is directly proportional to the mass of the attracting body. B) Gravity is the opposite of the electromagnetic force. C) Gravity is the result of curved spacetime. D) Gravity can affect only massive particles, not massless photons. E) Gravity is inversely proportion to the radius of the body. 32) Which of these does not depend on a close binary system to occur? 32) A) a nova B) a Type I supernova C) a Type II supernova D) All of these need mass transfer to occur. E) None of these depend on mass transfer. 33) The RR Lyrae stars all have periods of 33) A) several days. B) several hours. C) less than a second. D) several weeks. E) several minutes. 34) What perception of the Milky Way Galaxy did astronomers have in 1900? 34) A) They believed that the Milky Way was one of billions of galaxies in the universe. B) They believed we were one of billions galaxies in an expanding universe. C) They believed that the Milky Way was the entire universe. - 5 -
D) They believed that, because the Sun was at the center of the Milky Way, it was impossible to see the rest of the universe. E) They believed that the Earth rested inside concentric spheres, with the Milky Way stars fixed to the outermost sphere. 35) Most of the energy of the supernova is carried outward via a flood of 35) A) protons. B) gamma rays. C) neutrinos. D) helium nuclei. E) positrons. 36) The orbits of Population II stars have been compared to 36) A) comets around the Sun. B) the accretion disc around a black hole. C) binary stars. D) satellites around planets. E) planets around the Sun. 37) Neutron stars do not have 37) A) strong magnetic fields. B) large surface gravities, compared to the Sun. C) masses greater than 1.4 solar masses. D) rotation periods comparable to the Sun's. E) sizes comparable to large cities. 38) The iron we commonly find in our surroundings came from 38) A) the iron core of a massive star which exploded as a type I supernova. B) jets ejected by a rapidly spinning pulsar. C) material ejected by a nova explosion. D) planetary nebulae. E) decay of nickel 56 and cobalt 56 in a supernova remnant. 39) The vast majority of pulsars are known only from their pulses in: 39) A) radio waves. B) visible light. C) microwaves. D) X-rays. E) gamma rays. 40) As a star evolves, heavier elements tend to form by various processes. Which of the following is not one of these processes? 40) A) fusion of like nuclei B) helium capture C) neutronization D) the s process E) proton capture and neutron capture - 6 -