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Omega Sagittarii
Binary star system in the constellation of Sagittarius / From Wikipedia, the free encyclopedia
Omega Sagittarii, which is Latinized from ω Sagittarii, is a binary star system in the constellation of Sagittarius,[9] near the eastern constellation border with Capricornus. It is formally named Terebellum /tɛrɪˈbɛləm/.[10][11] This system has a yellow hue and is faintly visible to the naked eye with an apparent visual magnitude of 4.70.[2] It is located at a distance of 76 light years away from the Sun based on parallax,[1] and is drifting closer with a radial velocity of −16 km/s.[1] The position of this star near the ecliptic means it is subject to lunar occultations.[12]
Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
---|---|
Constellation | Sagittarius |
Right ascension | 19h 55m 50.36255s[1] |
Declination | −26° 17′ 57.6933″[1] |
Apparent magnitude (V) | 4.70[2] |
Characteristics | |
Evolutionary stage | subgiant |
Spectral type | G5 IV[3] |
U−B color index | +0.32[4] |
B−V color index | +0.748±0.015[1] |
R−I color index | +0.37[4] |
Astrometry | |
Radial velocity (Rv) | −16.22±0.43[1] km/s |
Proper motion (μ) | RA: 203.96[5] mas/yr Dec.: 74.40[5] mas/yr |
Parallax (π) | 42.7159 ± 0.5538 mas[1] |
Distance | 76.4 ± 1.0 ly (23.4 ± 0.3 pc) |
Absolute magnitude (MV) | 2.64[2] |
Orbit[6] | |
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[7] | |
Mass | 1.52+0.08 −0.06 M☉ |
Radius | 2.87+0.37 −0.34[1] R☉ |
Luminosity | 7.1±0.1[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[8] km/s |
Age | 3.00+0.13 −0.61 Gyr |
Other designations | |
Database references | |
SIMBAD | data |
The members of this system orbit each other with a period of 4.6892 yr and an eccentricity of 0.82.[6] The visible component is a G-type subgiant star with a stellar classification of G5 IV.[3] It is three[7] billion years old and is spinning with a projected rotational velocity of 5.6 km/s.[8] The star is radiating seven[1] times the luminosity of the Sun from its photosphere at an effective temperature of 5,499 K.[7]