Delta Cephei has a period of about P = 5.25 days,
   and an average apparent V-band magnitide of about m(V) = 4.2.


   To find the absolute magnitude, use

              M(V)  =  -1  - 2.8*log10(period)

                    =  -3.0

   Now, use the distance modulus to calculate the distance


            (m - M)  =  4.2 - (-3.0)  =  7.2

                     =  5*log10(d) - 5


                           12.2/5
          -->     d  =  10

                     =  270 pc