Beta Ophiuchi
Beta Ophiuchi or β Ophiuchi, also named Cebalrai /ˌsɛbəlˈreɪ.iː/, is a star in the equatorial constellation of Ophiuchus. The apparent visual magnitude of this star is 2.7, which is readily visible to the naked eye even from urban skies. The distance to this star can be estimated using parallax measurements, yielding a value of 81.8 light-years (25.1 parsecs) from the Sun.
| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Ophiuchus |
| Right ascension | 17h 43m 28.35265s |
| Declination | +04° 34′ 02.2955″ |
| Apparent magnitude (V) | 2.749 (2.75 to 2.77) |
| Characteristics | |
| Spectral type | K2 III |
| U−B color index | +1.253 |
| B−V color index | +1.170 |
| Variable type | K-type giant, |
| Astrometry | |
| Radial velocity (Rv) | –12.53 km/s |
| Proper motion (μ) | RA: 41.45 mas/yr Dec.: +159.34 mas/yr |
| Parallax (π) | 39.85 ± 0.17 mas |
| Distance | 81.8 ± 0.3 ly (25.1 ± 0.1 pc) |
| Absolute magnitude (MV) | +0.77 ± 0.04 |
| Details | |
| Mass | 1.13 M☉ |
| Radius | 12.42 ± 0.13 R☉ |
| Luminosity | 63.4 ± 3.2 L☉ |
| Surface gravity (log g) | 2.22 cgs |
| Temperature | 4,467 K |
| Metallicity [Fe/H] | 0.04 dex |
| Rotational velocity (v sin i) | 5.4 km/s |
| Age | 3.82 ± 1.86 Gyr |
| Other designations | |
Cebalrai, Celbalrai, Cheleb, Kelb Alrai, Bet Oph, β Oph, β Ophiuchi, 60 Oph, 60 Ophiuchi, BD+04°3489, FK5 665, HD 161096, HIP 86742, HR 6603, SAO 122671 | |
| Database references | |
| SIMBAD | data |
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