FG Sagittae

FG Sagittae

A rapidly evolving variable star in the constellation Sagitta that has recently cooled and expanded. It is now a pulsating yellow supergiant but in 1955 was a more compact hot blue supergiant. It is surrounded by a glowing expanding planetary nebula, and it is thought that as the nebula gradually disperses the central star will again heat up and contract before eventually becoming a white dwarf.
References in periodicals archive ?
FG Sagittae is the central star of a faint, large planetary.
Maybe FG Sagittae is in an especially rapid evolutionary state, in which a helium-rich layer surrounding a dead carbon core suddenly erupted in a frenzy of nuclear fusion.
In FG Sagittae, and in a similar, recently discovered object known as Sakurai's Star (S&T: August 1997, page 20), we may be seeing giants on the rebound - right before our eyes.