BI Cygni — a luminous red supergiant in Cygnus BI Cygni BI Cygni is a red supergiant star in the constellation Cygnus, notable for a radius exceeding 1,000 times that of the Sun and for its role as an example of late-stage massive stell…
Stephenson 2-18 (St2-18): an extreme red supergiant Stephenson 2-18 Stephenson 2-18 (St2-18) is an extraordinary red supergiant near the open cluster Stephenson 2, notable for its enormous radius, high luminosity, cool spectrum and uncertain cluste…
