Astronomy- Ch 10-13 – Flashcards
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What is the sun powered by?
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Nuclear Energy
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Solar wind
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A flow of charged particles from the surface of the Sun
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Corona
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Outermost layer of solar atmosphere
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Chromosphere
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Middle layer of solar atmosphere
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Photosphere
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Visible surface of the Sun
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Convection zone
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Energy transported upward by rising hot gas
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Radiation zone
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Energy transported upward by photons
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Core
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Energy generated by nuclear fusion
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Avg. temp. in Sun
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5 million K
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Why does the Sun shine?
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because nuclear fusion in the core maintains both gravitational equilibrium between pressure and gravity and energy balance between thermal energy released in core and radiative energy lost from the Sun's surface.
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What is the Sun's structure, from inside out, the layers are?
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Core, Radiation zone, Convection zone, Photosphere, Chromosphere, Corona
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Fission
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Big nucleus splits into smaller pieces. (Nuclear power plants)
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Fusion
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Small nuclei stick together to make a bigger one. (Sun, stars)
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Why don't planets shine like stars?
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They are too lightweight
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What would happen inside the Sun if a slight rise in core temperature led to a rapid rise in fusion energy?
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The core would expand and cool.
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Which of these groups of particles has the greatest mass?
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four individual protons
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Which of these layers of the sun in coolest?
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photosphere
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Scientists estimate the central temperature of the Sun using
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mathematical models of the Sun
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Why do sunspots appear darker than their surroundings?
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they are cooler than their surroundings
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At the center if the Sun, fusion converts hydrogen into
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helium,energy, and neutrinos
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Solar energy leaves the core if the Sun in the form of
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photons
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How does the number of neutrinos passing through your body at night compare with the number passing through your body during the day?
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about the same
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What causes the cycle of solar activity?
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changes in the organization if the Sun's magnetic field
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Which of these things poses the greatest hazard to communication satellites ?
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particles from the Sun
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Stars can form most easily in clouds that are
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cold and dense
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a brown dwarf is
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an object not quite massive enough to be a star
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which of these stars has the hottest core?
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a red supergiant
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What happens to a low-mass star after a helium flash?
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its luminosity goes down
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What would you be most likely to find of you returned to the solar system in 10 billion years?
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a white dwarf
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which of these stars has the shortest life expectancy?
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a 1M sun star in a close binary system with a 2Msun star
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What happens to the core of a high-mass star after it runs out of hydrogen?
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it shrinks and heats up
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If the star Alpha Centauri were moved to a distance 10 times farther from earth than it is now, its parallax angle would
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Get smaller
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what do we need to measure in order to determine a star's luminosity?
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apparent brightness and distance
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what two pieces of information would you need in order to measure the masses of stars in eclipsing binary system?
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the time between eclipses and the average distance between the stars
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which of these stars has the coolest surface temperature
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a K star
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which of these stars is the most massive?
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a main-sequence A star
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which of these stars has the greatest surface temperature ?
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a supergiant A star
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Which of these stars has the largest radius?
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a supergiant A star
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which of these star clusters is youngest?
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a cluster containing stars of all colors
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which of these star clusters is oldest?
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a cluster whose brightest main-sequence stars are yellow
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Which of these objects has the smallest radius?
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a 1.2 M sun white dwarf
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Which of these objects has the largest radius?
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a 1.2 M sun white dwarf
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Which of these things has the smallest radius?
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the event horizon of a 3.0M sun black hole
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What would happen if the sun suddenly became a black hole without changing its mass
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Earth's orbit would not change
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which of these isolated neutron stars mist have had a binary companion?
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an isolated pulsar that pulses 600 times per second
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what would happen to a neutron star with an accretion disk orbiting in a direction opposite to the neutron star's spin?
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its spin would slow down
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Which of these binary system is most likely to contain a black hole?
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an X-ray binary containing an O star and another objects of equal mass
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how would a flashing red light appear as it fell into a black hole?
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it flashes would shift to the infrared part of the spectrum
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which of these black holes exerts the weakest tidal forces on an object near its event horizon?
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a 10^6 M sun black hole
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Where do gamma-ray bursts tend to come from?
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extremely distant galaxies
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These two stars have about the same luminosity— which one appears brighter the sun or the Alpha Centauri?
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The sun
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How would the apparent brightness of Alpha Centauri change if it were three times farther away?
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It would be only 1/9 as bright
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Which kind of star is hottest? A. M star B. F star C. A star D. K star
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A star
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Spectral Types (Hottest) O B A F G K M (Coolest) • Oh, Be A Fine Girl, Kiss Me (ca. 1920) • Only Boys Accepting Feminism Get Kissed Meaningfully (today)
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...
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To measure a star's luminosity, you need to know
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Its temperature and color
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What do the colors of stars in the Hertzsprung-Russell diagram tell us?
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The surface temperature of the star.
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Stars that begin their lives with the most mass live longer than less massive stars because it takes them a lot longer to use up their hydrogen fuel.
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No, more massive stars are much more luminous than low mass stars and use up their hydrogen faster, even though they have more of it.
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Why can't a cloud with less than 0.08 times the mass of the Sun become a star?
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It will never get hot enough for fusion to start.
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What happens to nuclear fusion when the hydrogen in a star's core runs low?
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It shifts from the core to a shell around the core.
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After the Sun becomes a red giant star and makes carbon in its core, why will it not make heavier elements?
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It will not be massive enough to make it hot enough for further reactions
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How does the life of a high-mass star differ from the Sun's life?
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-It forms much faster -It lives a shorter time on the main sequence -As a red giant or supergiant, it makes elements heavier than carbon -When it dies, it explodes in a tremendous supernova explosion
