Xi Ophiuchi
ξ Oph, Latinized as Xi Ophiuchi, is a visual binary star system in the equatorial constellation of Ophiuchus. It has a yellow-white hue and is faintly visible to the naked eye with a combined apparent visual magnitude of 4.39. The system is located approximately 57.1 light-years (17.5 parsecs) away from the Sun based on parallax, but is drifting closer with a radial velocity of -9 km/s.
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Ophiuchus |
| Right ascension | 17h 21m 00.37452s |
| Declination | −21° 06′ 46.5710″ |
| Apparent magnitude (V) | 4.39 |
| Characteristics | |
| Spectral type | F2V |
| U−B color index | -0.06 |
| B−V color index | +0.41 |
| Astrometry | |
| Radial velocity (Rv) | −8.73±0.12 km/s |
| Proper motion (μ) | RA: +265.543 mas/yr Dec.: -202.584 mas/yr |
| Parallax (π) | 57.0820 ± 0.1851 mas |
| Distance | 57.1 ± 0.2 ly (17.52 ± 0.06 pc) |
| Absolute magnitude (MV) | 3.19 |
| Details | |
| A | |
| Mass | 1.30 M☉ |
| Radius | 1.59±0.06 R☉ |
| Luminosity | 4.429±0.035 L☉ |
| Surface gravity (log g) | 4.15±0.10 cgs |
| Temperature | 6,611±80 K |
| Metallicity [Fe/H] | −0.27±0.07 dex |
| Rotational velocity (v sin i) | 20.2±0.7 km/s |
| Age | 916 Myr |
| Other designations | |
| Database references | |
| SIMBAD | data |
The magnitude 4.40 primary, designated component A, is an ordinary F-type main-sequence star with a stellar classification of F2V. It is 916 million years old and is rotating with a projected rotational velocity of 20 km/s. The star has 1.3 times the mass of the Sun and 1.6 times the Sun's radius. It is radiating 4.4 times the luminosity of the Sun from its photosphere at an effective temperature of 6,611 K.
The system is a source of X-ray emission. The orbiting companion, component B, is a magnitude 8.9 star at an angular separation of 35″ along a position angle of 27° from the primary, as of 2015. A magnitude 10.8 visual companion, component C, lies at a separation of 10.8″, as of 2004.
According to Richard H. Allen's Star Names: Their Lore and Meaning (1899), ξ Oph together with θ Oph formed the Sogdian Wajrik "the Magician", the Khorasmian Markhashik "the Serpent-bitten" and with η Oph the Coptic Tshiō, "the Snake", and Aggia, "the Magician".