Chi1 Sagittarii
Star in the constellation Sagittarius
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Chi1 Sagittarii (χ1 Sagittarii) is a binary star[9] system in the zodiac constellation of Sagittarius. The pair have a combined apparent visual magnitude of +5.03,[2] which is bright enough to be seen with the naked eye. Based upon a parallax of 13.25 mas,[3] it is located around 246 light years away. It is advancing through space in the general direction of the Earth with a radial velocity of −43.4 km/s.[6]
 | |
| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Sagittarius |
| Right ascension | 19h 25m 16.49013s[1] |
| Declination | −24° 30′ 30.8599″[1] |
| Apparent magnitude (V) | +5.03[2] (5.46 + 5.96)[3] |
| Characteristics | |
| Evolutionary stage | main sequence[4] |
| Spectral type | A3/5 IV/V[5] (A2IV + A5IV) |
| B−V color index | +0.23[2] |
| Astrometry | |
| Radial velocity (Rv) | −43.4±1.6[6] km/s |
| Proper motion (μ) | RA: +61.63[1] mas/yr Dec.: −50.66[1] mas/yr |
| Parallax (π) | 13.25±0.07 mas[3] |
| Distance | 246 ± 1 ly (75.5 ± 0.4 pc) |
| Absolute magnitude (MV) | +0.59[7] |
| Orbit[3] | |
| Period (P) | 5.6985±0.0015 yr |
| Semi-major axis (a) | 0.0664±0.0003″ |
| Eccentricity (e) | 0.7099±0.0033 |
| Inclination (i) | 93.02±0.50° |
| Longitude of the node (Ω) | 80.15±0.55° |
| Periastron epoch (T) | B 2023.9455±0.0010 |
| Argument of periastron (ω) (secondary) | 354.19±0.75° |
| Details[3] | |
| Chi1 Sgr A | |
| Mass | 2.09±0.02 M☉ |
| Chi1 Sgr B | |
| Mass | 1.78±0.01 M☉ |
| Other designations | |
| Chi1 Sgr, 47 Sgr, CPD−24°6721, HD 182369, HIP 95477, HR 7362, SAO 188101, WDS J19253-2431[8] | |
| Database references | |
| SIMBAD | data |
This is a visual binary with an orbital period of 5.6985 years, an eccentricity of 0.710, and an angular semimajor axis of 66.4 mas. The magnitude 5.46 primary, Chi1 Sagittarii A, has a mass 2.09 times that of the Sun, while the secondary, Chi1 Sagittarii B, has a mass 1.78 times solar and a magnitude of 5.96. Spectral types of A2IV and A5IV have been published for the primary and secondary component.[3] A spectrum of A3/5 IV/V has been published,[5] but Helmut Abt published spectral type of kA5hF0VmF0, typical of Am stars.[10] This notation indicates it has the calcium K-lines of an A5 star, and the hydrogen and metal lines of an F0 star.