Visual binary star system in the constellation Ophiuchus
 ;/td ;
! style="text-align: center; background-color: #FFFFC0;" colspan="2" | Observation dataEpoch J2000      Equinox J2000
! style="text-align:left" | Constellation
! style="text-align:left" | Right ascension
! style="text-align:left" | Declination
! style="text-align:left" | Apparent magnitude (V)
! style="background-color: #FFFFC0; text-align: center;" colspan="2"| Characteristics
! style="text-align:left" | Spectral type
! style="text-align:left" | U−B 
! style="text-align:left" | B−V 
 ;/th ; ;/tr ;
 ;/th ; ;/tr ;
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 away from the Sun based on parallax, but is drifting closer with a radial velocity of -9 km/s.
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 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 , 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".
References.
 ;templatestyles src="Reflist/styles.css" / ;