Stars and Galaxies 25-28 – Flashcards
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The more massive a galaxy is
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The faster it rotates
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A galaxy containing substantial amount of dark matter
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spin faster
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According to X-ray observations, the space between galaxies in a galactic cluster is
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Very hot
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Relative to luminous stellar matter will appear
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greater than the fraction in galaxies
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The hubble deep field in figure 25.10 shows a patch of sky that has the same angular size as
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The thickness of a piece of string
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Galaxies evolve by
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merging to form larger galaxies
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Acccording to current theories of galactic evolution, quasars occur
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early in the evoluntionary expiernence
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Many nearby galxies
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were more active in the past
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If light from a distant QUASAR did not pass through any intervening atomic hydrogen clouds then figute 25.3 would have to be redrawn to show
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few absorption features
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If figure 25.25 showed the Gravitational lens showed more massive quasar images would
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farther apart
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If a Observations from a large city are isotropic
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there are tall buildings in every direction
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The cosmological principle would be valid if we found that
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the observed structure of the universe depends on which direction we look
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When we use hubbles law to estimate the age of the universe, the answer we get
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is the same for all galaxies
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Olber's paradox is resolved by
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the finite age of the universe
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The data point in 26.11 "accelerating universe"
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allow a measurement of hubbles constant
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The galactic distance used to measure the acceleration of the universe are determined by observation of
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Exploding white dwarfs
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The observed accleration of the universe means that
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the amount of dark energy exceeds the total mass-energy
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On the basis of our current best estimate of the present mass density of the universe, astronomers think that
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the universe is infinite in extent and will expand forever
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The age of the universe is estimated to be
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greater than the age of the milky way galaxy
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The cosmic background radiation is observed to come from
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all directions equally
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Immediately after its birth the universe
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was dominated by photons
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Present day Grand unified theories unite all the fundamental forces except
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the gravational force
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About half a million years ago after the big bang, the universe had cooled to the point that
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protons and electrons could combine to form atoms
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one problem with the standard big bang model is that
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the temperature is almost the same everywhere
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According to our best estimates the line that best describes the universe in figure 27.10 "Flatness problems" is
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accelerating
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it is likely that the density of the universe is made up mostly of
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dark energy
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The horizon problem in the standard big bang model is solved by having the universe
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inflate rapidly early in its existence
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The structure we observe in the universe is the result of
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dark matter clumping long ago
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Elements more massive that lithium were not formed in the early universe because the temperature was
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too low
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matter and energy clumping in the early universe result in
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small but observable red shifts
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The "Assumption of Mediocrity" suggest
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life should be common throughout the cosmos
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The chemical elements that form the basic molecules for life
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throughout the cosmos
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Fossil records of early life- forms on Earth suggest that life began
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3.5 billlion years ago
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The discovery of bacteria on another planet would be an important discovery because bacteria
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are the lowest forms of life
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The least well known factor of the drake equation is
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the average lifetime of a technologicaly competent civilization
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Althought the habitable zone around a large B-Class star is large, we don't often look for life on planets because the star
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is too short live for life to evolve
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From the date shown in figure 28.12 "stellar habitable zone" and your knowledge of stellar properties the habitable zone surrounding a main sequence K-star
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is larger than a M type star
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In figure 28.16 Leakage were being redrawn for a planet spinning twice as fast , the new jagged edge would be
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compressed horizontally
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Radio telescope cannot simply scan the sky for signals because
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Many non living objects emit radio signal naturally
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The strongest radio wavelength emitter in the solar system is
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human made signals from earth
