BC Cygni
BC Cygni ( BC Cyg , HIP 100404 , BD + 37 3903 ) is a red supergiant and pulsating variable star of spectral type M3 . 5Ia in the constellation Cygnus . 
<triplet> BC Cygni <subj> red supergiant <obj> instance of <subj> pulsating variable star <obj> instance of <subj> Cygnus <obj> constellation