INSTRUCTIONS: Choose the one alternative that best completes the statement or answers the question.

1) What is happening inside a star while it expands into a red giant?A) It is not fusing any element; it is contracting and heating up.B) It is fusing hydrogen into helium in a shell outside the core.C) It is fusing hydrogen into helium in the core.D) It is fusing helium into carbon in the core.E) It is fusing helium into carbon in a shell outside the core.

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2) What is a planetary nebula?A) a disk of gas surrounding a protostar that may form into planetsB) the molecular cloud from which protostars formC) what is left of the planets around a star after a low-mass star has ended its lifeD) the expanding shell of gas that is left when a white dwarf explodes as a supernovaE) the expanding shell of gas that is no longer gravitationally held to the remnant of alow-mass star

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3) What causes the radio pulses of a pulsar?A) The star undergoes periodic explosions of nuclear fusion that generate radio emission.B) The star's orbiting companion periodically eclipses the radio waves emitted by the mainpulsar.

C) As the star spins, beams of radio radiation sweep through space. If one of the beamscrosses the earth, we observe a pulse.

D) The star vibrates.E) A black hole near the star absorbs energy and re-emits it as radio waves.

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4) Compared with stars in the disk, orbits of stars in the halo of a galaxyA) are elliptical, with random orientation.B) do not have to be around the galactic center.C) are relatively uniform to each other.D) do not have to pass through the plane of the galaxy.E) are elliptical but orbiting in the same direction.

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5) Which of the following types of galaxies are most spherical in shape?A) irregulars B) ellipticals C) lenticulars D) spirals

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6) Why are Cepheid variables important?A) Cepheids are pulsating variable stars, and their pulsation periods are directly related totheir true luminosities. Hence, we can use Cepheids as "standard candles" for distancemeasurements.

B) Cepheids are a type of young galaxy that helps us understand how galaxies form.C) Cepheids are supermassive stars that are on the verge of becoming supernovae andtherefore allow us to choose candidates to watch if we hope to observe a supernova in thenear future.

D) Cepheid variables are stars that vary in brightness because they harbor a black hole.

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7) What two quantities did Edwin Hubble plot against each other to discover the expansion of theUniverse?A) velocity and temperatureB) luminosity and temperatureC) luminosity and distanceD) velocity and distanceE) age and distance

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8) What do scientists mean by the critical density of the universe?A) the precise density marking the dividing line between a universe that has enough mass tocontract again and a universe that will continue to expand forever

B) the minimum density that a universe needs in order to form starsC) the minimum density that a universe needs in order to create hydrogenD) the average density of the space between galaxiesE) the minimum density that a universe needs in order to form galaxies

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9) What is a quasar?A) a starlike object that actually represents a bright patch of gas in the Milky WayB) another name for very bright stars of spectral type OC) the extremely bright center of a distant galaxy, thought to be powered by a massive blackhole

D) a very large galaxy thought to be formed by the merger of several smaller galaxies,typically found in the center of a galaxy cluster

E) a specialized astronomical instrument for observing distant stars

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10) What is meant by "dark energy"?A) any unknown force that opposes gravityB) the agent causing the universal expansion to accelerateC) highly energetic particles that are believed to constitute dark matterD) the energy associated with dark matter through E=mc2E) the total energy in the Universe after the Big Bang but before the first stars

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11) What do we mean by inflation?A) the sudden release of photons when a particle and antiparticle annihilate each otherB) what happened the instant after the Big BangC) the separation that occurs after two photons collide and create a particle and anantiparticle

D) a sudden expansion of the universe after the strong force froze out from the GUT forceE) the expansion of the universe that we still observe today

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12) Where do the photons in the cosmic background radiation originate?A) the end of the era of nucleiB) the end of the Planck eraC) during the era of galaxy formationD) the moment of the Big BangE) during the era of nucleosynthesis

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13) After a massive-star supernova, what is left behind?A) always a black holeB) either a neutron star or a black holeC) always a neutron starD) either a white dwarf or a neutron starE) always a white dwarf

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14) What is the thickness of the disk of the Milky Way?A) 100,000 light-yearsB) 1,000,000 light-yearsC) 1,000 light-yearsD) 10,000 light-yearsE) 100 light-years

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15) Where are most heavy elements made?A) in the Big Bang, when the universe first beganB) in the interstellar mediumC) in stars and supernovaeD) none of the aboveE) all of the above

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Answer KeyTestname: AS102SAMPLEFINAL

1) B2) E3) C4) A5) B6) A7) D8) A9) C10) B11) D12) A13) B14) C15) C

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