W Sagittarii
W Sagittarii (W Sgr) is a cepheid variable star in the constellation Sagittarius. It was temporarily referred to as Gamma-1 Sagittarii (γ¹ Sgr). It is an optical line-of-sight companion to the much brighter [Al Nasl] Gamma-2 which marks the "nozzle" ("spout") of the "teapot" asterism forming a large part of Sagittarius.
Variability
This variable star changes in apparent magnitude from 4.29m to 5.14m with a period of 7.6 days. Its change in brightness is accompanied by a change in spectral classification, from G2Ib to F4Ib. Based on its variability, W Sagittarii has been estimated to be approximately 1,500 light years from Earth.
Binary system
W Sagittarii also shows evidence of being a close binary star, as well has having two more distant 13th-magnitude optical companions, W Sagittarii B and C separated by 33 and 48 arcseconds respectively.
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