Why Does the Cepheid "Standard Candle" Have Limited Usefulness Beyond

question 44

Multiple Choice

Why does the Cepheid "standard candle" have limited usefulness beyond 100 Mpc?

• A) Distant galaxies are seen in the past, when Cepheid variables behaved differently than they do today.
• B) Distant galaxies are so young they do not contain Cepheids.
• C) Cepheids are too faint to be seen beyond that distance, even with HST.
• D) The light variability of Cepheids diminishes with distance so they do not appear to vary there.
• E) Older distant Cepheids are of population II, where the period-luminosity relation no longer works.

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