Zeta Ophiuchi
Zeta Ophiuchi (ζ Oph, ζ Ophiuchi) is a single star located in the constellation of Ophiuchus. It has an apparent visual magnitude of 2.6, making it the third-brightest star in the constellation. Parallax measurements give an estimated distance of roughly 366 light-years (112 parsecs) from the Earth. It is surrounded by the Sh2-27 "Cobold" nebula, the star's bow shock as it ploughs through dense dust clouds near the Rho Ophiuchi cloud complex.
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Ophiuchus |
| Right ascension | 16h 37m 09.53905s |
| Declination | −10° 34′ 01.5295″ |
| Apparent magnitude (V) | 2.56 - 2.58 |
| Characteristics | |
| Spectral type | O9.5 V |
| U−B color index | −0.857 |
| B−V color index | +0.032 |
| Variable type | γ Cas + β Cep |
| Astrometry | |
| Radial velocity (Rv) | −15.0 km/s |
| Proper motion (μ) | RA: +15.26 mas/yr Dec.: +24.79 mas/yr |
| Parallax (π) | 8.91 ± 0.20 mas |
| Distance | 366 ± 8 ly (112 ± 3 pc) |
| Absolute magnitude (MV) | −4.2 |
| Details | |
| Mass | 20.2 M☉ |
| Radius | 8.5 R☉ |
| Luminosity | 74,100 L☉ |
| Surface gravity (log g) | 3.58 cgs |
| Temperature | 34,300 (30,700-39,000) K |
| Rotational velocity (v sin i) | 400 km/s |
| Age | 3.0±0.3 Myr |
| Other designations | |
| Database references | |
| SIMBAD | data |
In April 2010, ζ Ophiuchi was occulted by asteroid 824 Anastasia.
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