18 Sagittarii
| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Sagittarius |
| Right ascension | 18h 25m 01.42751s |
| Declination | −30° 45′ 23.6292″ |
| Apparent magnitude (V) | 5.58 |
| Characteristics | |
| Evolutionary stage | giant star |
| Spectral type | K0 III |
| B−V color index | 1.138 |
| Astrometry | |
| Radial velocity (Rv) | −18.7±2.9 km/s |
| Proper motion (μ) | RA: −135.019 mas/yr Dec.: −70.932 mas/yr |
| Parallax (π) | 5.9260±0.2434 mas |
| Distance | 550 ± 20 ly (169 ± 7 pc) |
| Absolute magnitude (MV) | −0.93 |
| Details | |
| Radius | 8.9 R☉ |
| Luminosity | 309.45 L☉ |
| Surface gravity (log g) | 1.50 cgs |
| Temperature | 4,341 K |
| Metallicity [Fe/H] | −0.79 dex |
| Rotational velocity (v sin i) | 1.0 km/s |
| Other designations | |
| 18 Sgr, CD−30°15661, HD 169233, HIP 90260, HR 6888, SAO 210116 | |
| Database references | |
| SIMBAD | data |
18 Sagittarii is a single star in zodiac constellation of Sagittarius, located around 550 light years away from the Sun based on parallax. It is visible to the naked eye as a faint, orange-hued star with an apparent visual magnitude of 5.58. This object is moving closer to the Earth with a heliocentric radial velocity of −19 km/s.
This is an aging giant star with a stellar classification of K0 III, which indicates it has exhausted the hydrogen at its core and evolved away from the main sequence. It has expanded to about 9 times the Sun's radius and is radiating 309 times the Sun's luminosity from its enlarged photosphere at an effective temperature of 4,341. There is a much lower abundance of iron in the spectrum compared to the Sun.