Standard Candle Comparison
Cepheid Variable stars and Type 1a supernovae are both standard candles - objects of known luminosity used to estimate interstellar distances. Cepheid Variable stars have luminosities of around 100,000 times the luminosity of the sun, and can be viewed out to a distance of around 30 Megaparsecs. Type 1a supernovae have luminosities of approximately times the luminosity of the sun.
Approximately how far away can we observe type 1a supernovae, in Megaparsecs?
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1 solution
The intensity of light received from a source is proportional to r 2 P o w e r . This means that for a fixed intensity (the minimum intensity we can observe on Earth) the power is proportional to the square of the distance between the source and the observer.
This means we can take the ratio of luminosities (power) and square root it to find the ratio of distances.