ar ▁System . ▁It ▁is ▁a ▁sem ire g ular ▁variable ▁star ▁that ▁var ies ▁between ▁a ▁maximum ▁magnitude ▁of ▁ 6 . 1 4 ▁and ▁ ▁minimum ▁magnitude ▁of ▁ 6 . 4 2 . ▁Period s ▁of ▁ 2 7 . 7 , ▁ 1 4 3 . 3 ▁and ▁ 2 0 8 . 3 ▁days ▁have ▁been ▁recorded ▁in ▁its ▁p uls ations . ▁A Z , ▁AD ▁and ▁B I ▁Can is ▁Minor is ▁are ▁D elta ▁Sc uti ▁variables — short ▁period ▁( six ▁hours ▁at ▁most ) ▁p uls ating ▁stars ▁that ▁have ▁been ▁used ▁as ▁standard ▁cand les ▁and ▁as ▁subjects ▁to ▁study ▁ast rose ism ology . ▁A Z ▁is ▁of ▁spectral ▁type ▁A 5 IV , ▁and ▁ranges ▁between ▁magn itudes ▁ 6 . 4 4 ▁and ▁ 6 . 5 1 ▁over ▁a ▁period ▁of ▁ 2 . 3 ▁hours . ▁AD ▁has ▁a ▁spectral ▁type ▁of ▁F 2 III , ▁and ▁has ▁a ▁maximum ▁magnitude ▁of ▁ 9 . 2 1 ▁and ▁minimum ▁of ▁ 9 . 5 1 , ▁with ▁a ▁period ▁of ▁approximately ▁ 2 . 9 5 ▁hours . ▁B I ▁is ▁of ▁spectral ▁type ▁F 2 ▁with ▁an ▁apparent ▁magnitude ▁varying ▁around ▁ 9 . 1 9 ▁and ▁a ▁period ▁of ▁approximately ▁ 2 . 9 1 ▁hours . ▁ ▁At ▁least ▁three ▁red ▁gi ants ▁are ▁Mira ▁variables ▁in ▁Can is ▁Minor . ▁S ▁Can is ▁Minor is , ▁of ▁spectral ▁type ▁M 7 e ,