Astro Unit 3 Review – Flashcards
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General result of the proton-proton chain:
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4 H --> He + energy + other products
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The corona of the sun:
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is visible during a solar eclipse
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In the convective zone of the sun:
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Columns of hot gas rise, cool, and descend
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What part of the sun do we typically see?
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The photosphere
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In nuclear fusion, energy is produced because...
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The mass of the reacting chemicals is larger than that of the products
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When using different points in the Earth's orbit as a baseline for a parallax experiment it is best to do the observations how far apart?
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6 months
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One star is four times farther away than another. The parallax angle of the more distant star is:
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Four times smaller than that of a nearer star
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The parallax angle for the star Hadar is 0.010 arcseconds. How far away is Hadar?
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100 PC
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Put one of your thumbs at arm's length in front of your face. Now focus on something in the background and look through one eye at a time. What do you notice about your thumb?
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It appears to move faster when it is closer
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Star A is 4 times as luminous as star B. Star A is 2 times as far away as star B. Which star appears brighter and by how much?
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The stars appear the same brightness
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An "onion skin" shell burning structure, with elements up to iron being produced, develops in:
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A star much more massive than the sun
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What is at the center of the planetary nebula?
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Both the core of the dying star and something that will eventually become a white dwarf
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How do solar sized and smaller stars die? About how large are their remnants?
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They become white dwarfs about the size of earth
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What does not happen when an object approaches a black hole?
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It quickly gets sucked in even from a large distance
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How can we measure the mass of a black hole?
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Measure the speed of the orbit of a star in a binary system with the black hole
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What is the main requirement for a habitable zone?
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Liquid Water
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A star that is twice the mass of our sun would have a habitable zone that:
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Includes Mars but not Earth
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A star that is 75% of the mass of our sun would have a habitable zone that is:
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includes Venus only
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What factor is not in the Drake equation?
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Communication lag due to large distances between stars
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What does the Drake equation estimate?
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The number of technological civilizations in the Milky Way
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A large luminosity star...
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emits more light than a low luminosity star
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If a red giant appears the same brightness as a red main sequence star, which one is further away?
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The Red Giant
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The heaviest nuclei of all are formed...
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during a super nova explosion
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Fill in the blank in the following chemical reaction that occurs in the sun: Hydrogen-2 + Proton=?? + Energy
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Helium-3
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Which of the following has the smallest radius?
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A neutron star
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Why does the main sequence part of a star's life end?
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The hydrogen in the core is exhausted
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Which of the following will have the shortest lifetime on the main sequence?
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Main sequence star with the surface temperature of 20,000 K
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Many of the brightest 100 stars viewed from Earth are not on the main sequence because:
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The most luminous stars are giants and supergiants that have already finished their main sequence lifetimes
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A 2 solar mass main sequence star is at the same distance as a 0.2 solar mass main sequence star. Which star appears brighter?
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The 2 solar mass main sequence star appears brighter
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The temperature of the photosphere of the sun is closest to...
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6000 Kelvin
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An estimate of the number of communicating/technological civilizations that we expect in our galaxy would have a larger number if:
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The average number of planets that could support life for each star was longer
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If the sun had twice its mass, then which of the planets would be in the habitable zone?
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Jupiter
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In the transit method of finding extrasolar planets, the distance of the planet from it's star if found from:
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Kepler's 3rd law using the period of the planet's orbit (how often a transit occurs).
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How do astronomers measure the temperature of stars?
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By looking at which absorption lines are present in the star's spectrum.
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If two stars are the same temperature, how can one be more luminous than the other?
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It can have a larger radius.
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The largest fraction of nearby stars are:
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Red main sequence stars
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Review the graph in notebook 17 18
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Review the graph in notebook
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The parallax angle of a nearby star is measured to be 0.02 arcseconds. What is the distance to the star?
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50 parsecs
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Which of the following is the sequence of events for a 40 solar mass star? (one of the most massive stars)
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stellar nursery, protostar, blue star on main sequence, Type II supernova, black hole
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Star A is 9 times more luminous than Star B. The two stars appear the same brightness. What is true about their distances?
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Star A is 3 times further away than Star B
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Review #22
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Review #22
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What is the name of the slightly cooler layer of the sun just outside the photosphere?
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The chromosphere
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How does a star move on the H-R diagram during the period of time it is converting hydrogen to helium in it's core?
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It remains at a certain point on the main sequence and does not move
on the H-R diagram.
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If the entire mass of Earth were concentrated in a region the size of a marble, the resulting object would be:
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A Black Hole
