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18.6: Key Terms

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    66631
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    binary stars
    two stars that revolve about each other
    brown dwarf
    an object intermediate in size between a planet and a star; the approximate mass range is from about 1/100 of the mass of the Sun up to the lower mass limit for self-sustaining nuclear reactions, which is about 1/12 the mass of the Sun
    eclipsing binary
    a binary star in which the plane of revolution of the two stars is nearly edge-on to our line of sight, so that the light of one star is periodically diminished by the other passing in front of it
    H–R diagram
    (Hertzsprung–Russell diagram) a plot of luminosity against surface temperature (or spectral type) for a group of stars
    main sequence
    a sequence of stars on the Hertzsprung–Russell diagram, containing the majority of stars, that runs diagonally from the upper left to the lower right
    mass-luminosity relation
    the observed relation between the masses and luminosities of many (90% of all) stars
    selection effect
    the selection of sample data in a nonrandom way, causing the sample data to be unrepresentative of the entire data set
    spectroscopic binary
    a binary star in which the components are not resolved but whose binary nature is indicated by periodic variations in radial velocity, indicating orbital motion
    visual binary
    a binary star in which the two components are telescopically resolved
    white dwarf
    a low-mass star that has exhausted most or all of its nuclear fuel and has collapsed to a very small size; such a star is near its final state of life

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