W Sagittarii
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Sagittarius |
| Right ascension | 18h 05m 01.22643s |
| Declination | −29° 34′ 48.3222″ |
| Apparent magnitude (V) | 4.29 - 5.14 |
| Characteristics | |
| Aa1 | |
| Spectral type | F4 - G2Ib |
| U−B color index | +0.52 |
| B−V color index | +0.78 |
| Variable type | δ Cep |
| Aa2 | |
| Spectral type | A5V - F5V |
| Ab | |
| Spectral type | A0 V |
| Astrometry | |
| Radial velocity (Rv) | −28.04 km/s |
| Proper motion (μ) | RA: +4.372 mas/yr Dec.: −5.588 mas/yr |
| Parallax (π) | 2.365±0.1765 mas |
| Distance | 1,400 ± 100 ly (420 ± 30 pc) |
| Absolute magnitude (MV) | −3.76 |
| Orbit | |
| Primary | Aa1 |
| Companion | Aa2 |
| Period (P) | 4.33±0.01 yr |
| Semi-major axis (a) | 12.9 ± 0.3" (5.67 ± 0.13 AU) |
| Eccentricity (e) | 0.41 ± 0.02 |
| Inclination (i) | 7.0 ± 0.8° |
| Longitude of the node (Ω) | 68.4 ± 4.0° |
| Periastron epoch (T) | 2004.16 ± 0.01 |
| Argument of periastron (ω) (secondary) | 328.0 ± 1.3° |
| Orbit | |
| Primary | Aa |
| Companion | Ab |
| Period (P) | 172.9 yr |
| Semi-major axis (a) | 63 AU |
| Details | |
| Aa | |
| Mass | 5.8 M☉ |
| Radius | 61.0 R☉ |
| Luminosity | 2,690 L☉ |
| Surface gravity (log g) | 1.50 - 2.15 cgs |
| Temperature | 5,380 - 6,474 K |
| Metallicity [Fe/H] | +0.02 dex |
| Aa2 | |
| Mass | 1.4 - 2.0 M☉ |
| Ab | |
| Mass | 2.2 M☉ |
| Other designations | |
| γ1 Sgr, W Sagittarii, HR 6742, HD 164975, SAO 186237, HIP 88567, ADS 11029, CCDM 18050-2935 | |
| Database references | |
| SIMBAD | data |
W Sagittarii (W Sgr, Gamma1 Sagittarii (γ1 Sgr)) is a multiple star system star in the constellation Sagittarius, and a Cepheid variable star.
W Sagittarii is an optical line-of-sight companion nearly a degree from the much brighter γ2 Sgr (Al Nasl) which marks the nozzle or spout of the teapot asterism.