Sigma Aquarii

Sigma Aquarii (σ Aqr, σ Aquarii) is the Bayer designation for a double star in the equatorial constellation of Aquarius. It is visible to the naked eye with an apparent visual magnitude of 4.81. Based upon parallax measurements, the distance to this star is roughly 290 light-years (89 parsecs).

Sigma Aquarii is an astrometric binary with an orbital period of 654 days. The primary component has a stellar classification of A0 IVs, indicating that it is a subgiant star. This is categorized as an Am star, meaning that it is a chemically peculiar. The spectrum displays at least double the normal abundances of elements like magnesium, aluminum and silicon, while helium and scandium are under-abundant.