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| The sun belongs to what population of stars |
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| the precise density marking the dividing line between a universe that has enough mass to contract again and a universe that will continue to expand forever |
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| The value of the Hubble parameter is closest to |
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| the rotation curve it flat |
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| We know the galaxy has a massive halo because |
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| How does a lenticular galaxy differ from a spiral galaxy? |
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| what is the most accurate way to determine the distance to a nearby galaxy |
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| interstellar dust reflects more blue light than red light |
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| Why are reflection nebulae blue? |
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| Approx. how long did the era of nucleosynthesis last? |
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| how is the energy that powers radio galaxies, quasars, and other active galactic nuclei produced? |
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| all elements besides hydrogen and helium |
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| what do astronomers consider heavy elements? |
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| the extremely bright center of a distant galaxy, though to be powered by a massive black hole |
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| which population of stars have the highest metalicity |
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| about 10 light-hours across |
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| if an object doubles its luminosity in 10 hours, how large can the emitting source of light be |
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| emission nebulae are what color |
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| we don't know! - but we call it dark energy |
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| what might be causing the universe to accelerate |
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| according to the Hubble law, a galaxy that is farther away will be |
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| their gravity is strong enough to hold them together against the expansion of the universe |
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| Why isn;t space expanding within systems such as our solar system or the Milky Way? |
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| The motions of the gas and starsat the center indicate that it contains a million solar masses within a region about 1 parsec across |
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| What evidence supports the theory that there is ablack hole at the center of our galaxy? |
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| mostly from the big bang, with a small contribution from stellar nucleosynthesis |
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| helium mostly originates from |
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| the predominance of matter over antimatter |
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| THIS is not one of the primary observations aupporting the Big Bang model |
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| The light from the galaxy as it was 100 million years ago and it is redshifted |
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| I observe a galaxy that is 100 million light-years away: what do I see? |
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| the galaxy cluster to which the Milky Way belongs |
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| they may have had rocky planets around them |
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| THIS cannot be true of the very first stars formed in the universe |
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| Approximately how long does it take the Sun to orbit the Milky Way Galaxy? |
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| The cosmological model that best fits the observations of the universe is the ___ model |
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| trigonometric parallax, spectroscopic parallax, Cepheid variables, Type Ia supernovae |
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| List the techniques used to determine distance from closest to farthest |
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| Interstellar extinction makes stars appear |
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| the nearest large spiral galaxy |
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| According to the big bang theory, the universe is how old? |
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| the agent causing the universal expansion to accelerate |
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| what is meant by "dark energy?" |
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| isotropic and homogeneous |
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| The Cosmological Principle says that on the large scale, the universe is |
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| Cephieds are pulsating variable stars |
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| Why are Cehpeid variables important? |
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| The recession velocity of a galaxy is directly proportional to its distance from us |
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| An example of a quasar is |
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| the measurements show that the expansion is accelerating, rather than slowing under the influence of gravity |
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| Recent measurements of expansion rate of the universe reveal that the expansion rate oftheu niverse is doing something astronomers did not expect. What is that? |
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| according to the big bang theory, the center from which everything is expanding is |
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| What is the diameter of the disk of the Milky Way? |
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| T/F The larger the value of Hubble's constant, the more rapid the expansion of the universe and hence the younger the universe. |
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| T/F If inflation really occurred, then our observable is only a tiny portion of the entire universe born in the big bang. |
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| T/F the sun is located at the edge of the galaxy, approximately 50,000 light-years from the galactic center |
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| T/F If we learn that is universe is a recollapsing unvierse, it will mean that the universe is presently contracting, rather than expanding as generally believed |
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| T/F although it is difficult to tell from our vantage point inside the galaxy, astronomers suspect that the milky way is a barred spiral |
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| the observed composition of ordinary matter in the universe - roughly 75% hydrogen and 25% helium - closely matches theoretical predictions based on the big bang model |
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| T/F the star-gas-star cycle will continue foreber because stars are continually recycling gas |
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| T/F most of the current star formation in the milky way occurs in the spiral arms |
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| T/F quasars radiate most of their ebergy as radio emission |
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| T/F galaxy mergers takes hundreds of millions of years to complete |
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| T/F massive-star supernovae and white-dwarf supernovae work equally well as standard candles for measuring cosmic distances |
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| T/F almost all elements heavier than hydrogen and helium were made of stars and supernovae |
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