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Cepheid Variable Stars as Cosmic Distance Rulers

-- robin | February 12, 2020

Question:

this is about Cepheid variables. I understand there’s a relation between their period and apparent magnitude, but to find their distance you need to know their absolute magnitude. How is this done? Can you use parallax method to determine distance of a close Cepheid and thus calibrate the relation period/luminosity/distance? Or how is it done? Thanks, Robin.

-- robin

Answer:

It is the period-luminosity relation for Cepheid variable stars that provides a measurement of the absolute magnitude. You will find a very nice description of this technique, with a worked example, on the Australia Telescope National Facility web site which should give you all of the details which support this astronomical distance measurement technique.

-- Jeff Mangum

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