Xi Ophiuchi

ξ Oph, Latinized as Xi Ophiuchi, is a visual binary star^[9] system in the equatorial constellation of Ophiuchus.^[2] It has a yellow-white hue and is faintly visible to the naked eye with a combined apparent visual magnitude of 4.39.^[2] 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.^[1]

Xi Ophiuchi

Location of ξ Ophiuchi (circled)
Observation data Epoch J2000      Equinox J2000
Constellation	Ophiuchus
Right ascension	17h 21m 00.37452s[1]
Declination	−21° 06′ 46.5710″[1]
Apparent magnitude (V)	4.39[2]
Characteristics
Spectral type	F2V[3]
U−B color index	−0.06[4]
B−V color index	+0.41[4]
Astrometry
Radial velocity (Rv)	−8.73±0.12[1] km/s
Proper motion (μ)	RA: +265.543 mas/yr[1] Dec.: −202.584 mas/yr[1]
Parallax (π)	57.0820±0.1851 mas[1]
Distance	57.1 ± 0.2 ly (17.52 ± 0.06 pc)
Absolute magnitude (MV)	3.19[2]
Details[5]
A
Mass	1.30 M☉
Radius	1.59±0.06 R☉
Luminosity	4.429±0.035[6] 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[7] Myr
Other designations
ξ Oph, 40 Oph, BD−20°4731, FK5 917, GC 23423, GJ 670, HD 156897, HIP 84893, HR 6445, SAO 185296, CCDM J17210-2107AB, WDS J17210-2107AB, LTT 6908[8]
Database references
SIMBAD	A
	B

The magnitude 4.40^[10] primary, designated component A, is an ordinary F-type main-sequence star with a stellar classification of F2V.^[3] It is 916^[7] 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.^[5] It is radiating 4.4^[6] times the luminosity of the Sun from its photosphere at an effective temperature of 6,611 K.^[5]

The system is a source of X-ray emission.^[11] The orbiting companion, component B, is a magnitude 8.9 star at an angular separation of 4.1″ along a position angle of 26° from the primary, as of 2016. A magnitude 10.8 visual companion, component C, lies at a separation of 10.8″, as of 2004.^[10]

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".^[12] The name Aggia for this star appears in a 1971 NASA list of star names^[13] and in a 2023 list of target stars for the Habitable Worlds Observatory.^[14] As of June 2025^[update], it does not appear in the IAU Catalog of Star Names.^[15]