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    Why did Henrietta Leavitt have to assume that the Cepheids she was analysing were roughly the same distance away?

    Is it because by assuming this, the intrinsic brightness of each variable can be calculated more accurately as distance is not affecting the observed brightness (when comparing each Cepheid)?

    Thanks!
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    (Original post by park1996)
    Why did Henrietta Leavitt have to assume that the Cepheids she was analysing were roughly the same distance away?

    Is it because by assuming this, the intrinsic brightness of each variable can be calculated more accurately as distance is not affecting the observed brightness (when comparing each Cepheid)?

    Thanks!
    yeah.
    well the apparent magnitude of cephid variable stars at unknown and likely very different distances doesn't help you establish a 'standard candle' for the reason you give.
    As you've probably read, she was comparing the period of cephids with others in the same cluster so it wasn't a wild assumption.
 
 
 
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