May / June (Usually visible from southern latitudes)
Delta Circini's close companion in the sky is HR 5661, a luminousblue star that lies somewhat farther from the Sun. Both stars are extremely luminous, but Delta Circini is the more luminous of the two, and thus the brighter in the skies of Earth. Both stars shine against the rich backdrop of the Milky Way. Imagery provided by Aladin sky atlas
An immensely distant, but highly luminousstar that lies more than two thousand light years from Earth. The main star in this system is of the intensely hot O-typeclassification, with a surface temperature of 25,000 K or even greater. This primaryO-typestar is in fact a close triple system, so close in fact that the gravity of the component stars causes their shapes to stretch and deform, and the apparent magnitude of the entire system to vary. Delta Circini also has another companion star, Delta Circini B, more distant from the close central triplets. This is apparently a yellowdwarf like our own Sun, though it is not currently known whether this companion follows an orbit around the main triple system.
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