What brighter standard candles, which must be calibrated using Cepheid distances, are now used to measure objects billions of light-years away?
Answer
Type Ia supernovae
While Cepheid variables are foundational, measuring objects extending to billions of light-years requires even brighter markers. Type Ia supernovae, which are the explosions of white dwarf stars, currently fulfill this role as crucial standard candles for extreme distances. However, their reliability depends entirely on the preceding rung of the distance ladder; their intrinsic luminosity must first be calibrated using the distances derived from Cepheid variable stars, meaning any initial error in the Cepheid measurement is proportionally magnified over greater cosmological scales.
Related Questions
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