Once astronomers obtain the apparent magnitude for a Cepheid variable star by direct observation and the absolute magnitude from the period-luminosity relation, what do they need to use to find its distance?

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Quizplus · Accepted Answer

The distance-magnitude relationship, also known as the distance modulus formula, is used to calculate the distance to a star when its apparent magnitude and absolute magnitude are known. This method is particularly useful for distant objects like Cepheid variable stars, where direct parallax measurements are not feasible.

Once Astronomers Obtain the Apparent Magnitude for a Cepheid Variable