Light curves of two RR Lyr variable stars in the Draco dwarf galaxy
show that the mean apparent magnitude is about m = +20.0.


              Q:  Suppose the average absolute magnitude of RR Lyr stars
                     were M = +2.0.  Determine the distance to
                     the Draco dwarf galaxy using light curves above.


                      (m - M)  =  5 log d  -  5

                      20 - 2   =  5 log d  -  5

                        18     =  5 log d  -  5

                                  (18 + 5)/5
                          d  =  10             

                             =   approx 40,000 pc



              Q:  Suppose the average absolute magnitude of RR Lyr stars
                     were M = -2.0.  Determine the distance to
                     the Draco dwarf galaxy using light curves above.


                      (m - M)  =  5 log d  -  5

                     20 - (-2) =  5 log d  -  5

                        22     =  5 log d  -  5

                                  (22 + 5)/5
                          d  =  10             

                             =   approx 250,000 pc