Beta2 Sagittarii
| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Sagittarius |
| Right ascension | 19h 23m 13.13745s |
| Declination | −44° 47′ 59.2051″ |
| Apparent magnitude (V) | +4.29 |
| Characteristics | |
| Spectral type | F2/3 V or F2 III |
| U−B color index | +0.07 |
| B−V color index | +0.34 |
| Astrometry | |
| Radial velocity (Rv) | +19.0 km/s |
| Proper motion (μ) | RA: +93.45 mas/yr Dec.: −54.09 mas/yr |
| Parallax (π) | 24.31±0.19 mas |
| Distance | 134 ± 1 ly (41.1 ± 0.3 pc) |
| Absolute magnitude (MV) | +1.20 |
| Details | |
| Mass | 1.43 M☉ |
| Luminosity | 20 L☉ |
| Surface gravity (log g) | 3.57 cgs |
| Temperature | 7,035±239 K |
| Metallicity [Fe/H] | −0.54 dex |
| Rotational velocity (v sin i) | 155 km/s |
| Age | 933 Myr |
| Other designations | |
| Arkab Posterior, β2 Sgr, CD−45°13171, HD 181623, HIP 95294, HR 7343, SAO 229654 | |
| Database references | |
| SIMBAD | data |
Beta2 Sagittarii (β2 Sagittarii, abbreviated Beta2 Sgr, β2 Sgr) is a star in the zodiac constellation of Sagittarius. It is visible to the naked eye, having an apparent visual magnitude of +4.29. Based upon an annual parallax shift of 24.31 mas as seen from Earth, it is located 134 light-years from the Sun.
Based upon variations in its proper motion, this is a probable astrometric binary system. As such, its two components would be designated Beta2 Sagittarii A (officially named Arkab Posterior /ˈɑːrkæb pɒˈstɪəriər/, the traditional name of the system) and B.