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Delta Cephei, a star that can be seen with the naked-eye, is a Cepheid variable star in the circumpolar constellation of Cepheus. Design an observational procedure to determine the distance to this star. Your design should include the following: Ɣ the observations that should be made Ɣ how you could process and analyse these observations to find the distance to the star.

Measure apparent magnitude of Delta-Cephei (1)

With the aid of reference stars (1)

Repeat on many (consecutive) nights (1)

Plot a light curve of Delta-Cephei and determine its period (1)

Determine absolute magnitude from period-luminosity relationship (Figure 16)

(1) Calculate distance using distance modulus formula and average apparent magnitude of Delta-Cephei (1)