18 Sagittarii
Star in the constellation Sagittarius
From Wikipedia, the free encyclopedia
18 Sagittarii is a single[7] star in zodiac constellation of Sagittarius,[6] located around 570 light years away from the Sun based on parallax.[2] It is visible to the naked eye as a faint, orange-hued star with an apparent visual magnitude of 5.58.[1] This object is moving closer to the Earth with a heliocentric radial velocity of â19 km/s.[1]
| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Sagittarius[1] |
| Right ascension | 18h 25m 01.42727s[2] |
| Declination | â30° 45â² 23.6167â³[2] |
| Apparent magnitude (V) | 5.58[1] |
| Characteristics | |
| Evolutionary stage | red giant branch[2] |
| Spectral type | K0 III[3] |
| BâV color index | 1.138[4] |
| Astrometry | |
| Radial velocity (Rv) | â18.7±2.9[1] km/s |
| Proper motion (μ) | RA: â134.805[2] mas/yr Dec.: â71.730[2] mas/yr |
| Parallax (Ï) | 5.7300±0.1342 mas[2] |
| Distance | 570 ± 10 ly (175 ± 4 pc) |
| Absolute magnitude (MV) | â0.93[4] |
| Details | |
| Radius | 29[5] Râ |
| Luminosity | 309[1] Lâ |
| Surface gravity (log g) | 1.50[4] cgs |
| Temperature | 4,341[4] K |
| Metallicity [Fe/H] | â0.79[4] dex |
| Rotational velocity (v sin i) | 1.0[4] km/s |
| Other designations | |
| 18 Sgr, CDâ30°15661, HD 169233, HIP 90260, HR 6888, SAO 210116[6] | |
| Database references | |
| SIMBAD | data |
This is an aging giant star with a stellar classification of K0 III,[3] which indicates it has exhausted the hydrogen at its core and evolved away from the main sequence. It has expanded to about 29 times the Sun's radius[5] and is radiating 309 times the Sun's luminosity[1] from its enlarged photosphere at an effective temperature of 4,341 K.[4] There is a much lower abundance of iron in the spectrum compared to the Sun.[4]