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    hey, can anyone explain to me how cepheid variables are used in determining big distances?
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    their luminosity is proportional to the time period of their pulsing, so you can determine their distance by measurement of their observed intensity, using I = L/(4pi*D^2). I think.
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    do they pulsate?
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    (Original post by Asian cutie)
    do they pulsate?
    yeah
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    (Original post by Mathemagician)
    hey, can anyone explain to me how cepheid variables are used in determining big distances?
    pulled this out of a markscheme:

    cepheid variables stars which luminousity varies with time
    work out time period (max to max luminousity)
    work out luminousity
    work out intensity at earths surface
    use L= 4piD^2.I to work out D
    distance calulated is approximate to galaxy the cepheid variable is in

    that is what the markscheme said - they dont really required any more detail, well in edexcel normal anyway

    pk
 
 
 
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