Del

Its story

Delta Circini is an extraordinarily massive hierarchical triple system of very hot O- and B-type stars, some 2,300 light-years away. At its core, two giants —an O8 just starting to evolve and an O9.5 main-sequence star— eclipse each other every 3.9 days, deformed by mutual gravity into ellipsoidal shapes. A third B0.5 star orbits them on a long eccentric path of about 1,603 days: a brutal mechanism hidden inside the modest southern Compass.