W Sagittarii
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Sagittarius |
| Right ascension | 18h 05m 01.3s |
| Declination | -29° 34' 48" |
| Apparent magnitude (V) | 4.66 (mean) |
| Distance | 2000 ± 1200 ly (600 ± 370 pc) |
| Spectral type | F4-G1Ib |
| Other designations | |
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.[1]
It has been estimated to be approximately 1500 light years from the Earth.
Variability
This variable star changes in apparent magnitude from 4.3m to 5.1m with a period of 7.59 days. Its change in brightness is accompanied by a change in spectral classification, from G1 to F4. 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.
References
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