· · · ·
Proper NameNone
Bayer DesignationGamma Sagittae
Flamsteed Number12 Sagittae
HR (BSC)7635
Right Ascension19h 58m 45s
Declination+19° 29' 32"
Distance258 light years
79 parsecs
MagnitudeApparent: +3.5
Absolute: -1.0
Spectral ClassM0III red giant
Optimum VisibilityAugust
NotesAt the heart of this red giant lies an inert core of exhausted matter, around which fusion still continues in shells of material spreading out into space. The star shows indications of pulsations characeristic of a variable star of the Mira type.

One of a narrow, tapering group of four stars that together form the shape of Sagitta, the Arrow. Gamma Sagittae (which is actually the brightest of the four stars, despite its 'Gamma' designation) marks the tip of the Arrow, pointing northeastwards towards Vulpecula the Fox and Cygnus the Swan beyond. Gamma Sagittae is not only the brightest of the four main stars of Sagitta, but also the closest to the Solar System at a distance of some 258 light years.

Gamma Sagittae is an ancient red giant star nearly a billion years old. It is so old, in fact, that its core is now exhausted and dead, but fusion continues in shells of matter extending out from the original heart of the star. These reach out to a diameter of more than half an Astronomical Unit, so that if Gamma Sagittae lay at the centre of the Solar System, its outer shell would extend approximately halfway to the orbit of Mercury.


Related Entries