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21 Cards in this Set
- Front
- Back
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The largest terrestrial planet and jovian planet are, respectively:
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earth and Jupiter
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Which of the following three kinds of objects resides closer to the Sun on average?
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asteroids
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Planetary orbits are:
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fairly circular and in the same plane.
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The composition of the solar nebula was 98%
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hydrogen and helium.
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What's the leading theory for the origin of the Moon?
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It formed from the material ejected in a giant impact.
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About how old is the solar system?
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4.5 billion years
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The extrasolar planets discovered so far most resemble
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jovian planets.
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How many extrasolar planets have been detected as of 2006?
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between a hundred and a thousand
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Sirius is a star with spectral type A star and Rigel is a star with spectral type B star. What can we conclude?
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Rigel has a higher surface temperature than Sirius.
This is true because the spectral sequence from hot to cool is OBAFGKM, which means spectral type B is hotter than spectral type A. |
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To calculate the masses of stars in a binary system, we must measure their _________.
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We can then apply Newton's version of Kepler's third law to find the sum of their masses.
orbital period and average orbital distance |
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Careful measurements reveal that a star maintains a steady apparent brightness at most times, except that at precise intervals of 73 hours the star becomes dimmer for about 2 hours. The most likely explanation is that _________.
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the star is a member of an eclipsing binary star system
The dimming comes during periodic eclipses. |
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Which group represents the most common type of stars?
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Cool, dim, low-mass M stars are the most common type of star by far.
These stars are high up on the diagram, meaning they re very luminous, and far to the left, which means they are hot and therefore emit most of their radiation as ultraviolet light. |
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Which group represents stars fusing hydrogen in their cores?
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All main sequence stars fuse hydrogen in their cores.
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Which group represents stars that have no ongoing nuclear fusion?
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White dwarfs no longer generate energy through fusion.
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You observe a star and you want to plot it on an H-R diagram. You will need to measure all of the following, except the star's _________.
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You do not need to know mass to plot a star on the H-R diagram.
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The approximate main-sequence lifetime of a star of spectral type O is _________.
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O stars are the shortest-lived of all stars, because they are the most massive and therefore the most luminous.
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How did astronomers discover the relationship between spectral type and mass for main sequence stars?
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By measuring the masses and spectral types of main-sequence stars in binary systems.
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The choices below each describe the appearance of an H-R diagram for a different star cluster. Which cluster is the youngest?
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Only O stars have died, so the cluster is no more than a few million years old.
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The choices below each describe the appearance of an H-R diagram for a different star cluster. Which cluster is most likely to be located in the halo of our galaxy?
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The diagram shows main-sequence stars of spectral types G, K, and M, along with numerous giants and white dwarfs.
This is an old cluster so it must be a globular cluster, and most globular clusters are in the halo of the galaxy. |
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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 an eclipsing binary system?
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the time between eclipses and the average distance between the stars
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