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…
Chi Cygni — a Mira-type pulsating red giant in Cygnus Chi Cygni Chi Cygni is a Mira-class pulsating red giant in Cygnus, notable for very large visual brightness changes and an extended atmosphere hundreds of times larger than the Sun.
