Omega Sagittarii
| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Sagittarius |
| Right ascension | 19h 55m 50.36255s |
| Declination | −26° 17′ 57.6933″ |
| Apparent magnitude (V) | 4.70 |
| Characteristics | |
| Evolutionary stage | subgiant |
| Spectral type | G5 IV |
| U−B color index | +0.32 |
| B−V color index | +0.748±0.015 |
| R−I color index | +0.37 |
| Astrometry | |
| Radial velocity (Rv) | −16.22±0.43 km/s |
| Proper motion (μ) | RA: 203.96 mas/yr Dec.: 74.40 mas/yr |
| Parallax (π) | 42.7159±0.5538 mas |
| Distance | 76.4 ± 1.0 ly (23.4 ± 0.3 pc) |
| Absolute magnitude (MV) | 2.64 |
| Orbit | |
| Period (P) | 1,712.74±0.29 d |
| Semi-major axis (a) | ≥ 1.1044 ± 0.0051 AU |
| Eccentricity (e) | 0.8200±0.0012 |
| Periastron epoch (T) | 57549.31±0.20 HJD |
| Argument of periastron (ω) (secondary) | 141.17±0.33° |
| Semi-amplitude (K1) (primary) | 12.255±0.041 km/s |
| Details | |
| Mass | 1.52+0.08 −0.06 M☉ |
| Radius | 2.87+0.37 −0.34 R☉ |
| Luminosity | 7.1±0.1 L☉ |
| Surface gravity (log g) | 3.64±0.05 cgs |
| Temperature | 5,499±91 K |
| Metallicity [Fe/H] | 0.06±0.06 dex |
| Rotational velocity (v sin i) | 5.6 km/s |
| Age | 3.00+0.13 −0.61 Gyr |
| Other designations | |
| Terebellum, ψ Sgr, 58 Sagittarii, CPD−26°6880, FK5 1629, GC 27583, GJ 770.1, GJ 9673, HD 188376, HIP 98066, HR 7597, SAO 188722, PPM 270451 | |
| Database references | |
| SIMBAD | data |
Omega Sagittarii, which is Latinized from ω Sagittarii, is a binary star system in the constellation of Sagittarius, near the eastern constellation border with Capricornus. It is formally named Terebellum /tɛrɪˈbɛləm/. This system has a yellow hue and is faintly visible to the naked eye with an apparent visual magnitude of 4.70. It is located at a distance of 76 light years away from the Sun based on parallax, and is drifting closer with a radial velocity of −16 km/s. The position of this star near the ecliptic means it is subject to lunar occultations.
The members of this system orbit each other with a period of 4.6892 yr and an eccentricity of 0.82. The visible component is a G-type subgiant star with a stellar classification of G5 IV. It is three billion years old and is spinning with a projected rotational velocity of 5.6 km/s. The star is radiating seven times the luminosity of the Sun from its photosphere at an effective temperature of 5,499 K.