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]
Distance57.1 ± 0.2 ly
(17.52 ± 0.06 pc)
Absolute magnitude (MV)3.19[2]
Details[5]
A
Mass1.30 M☉
Radius1.59±0.06 R☉
Luminosity4.429±0.035[6] L☉
Surface gravity (log g)4.15±0.10 cgs
Temperature6,611±80 K
Metallicity [Fe/H]−0.27±0.07 dex
Rotational velocity (v sin i)20.2±0.7 km/s
Age916[7] Myr
Other designations
ξ Oph, 40 Ophiuchi, BD−20°4731, FK5 917, GC 23423, HD 156897, HIP 84893, HR 6445, SAO 185296, CCDM J17210-2107AB, WDS J17210-2107AB, LTT 6908[8]
Database references
SIMBADdata

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 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.[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]

References
  1. Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.
  2. Anderson, E.; Francis, Ch. (2012). "XHIP: An extended hipparcos compilation". Astronomy Letters. 38 (5): 331. arXiv:1108.4971. Bibcode:2012AstL...38..331A. doi:10.1134/S1063773712050015. S2CID 119257644. Vizier catalog entry
  3. Gray, R. O.; Corbally, C. J.; Garrison, R. F.; McFadden, M. T.; Bubar, E. J.; McGahee, C. E.; O'Donoghue, A. A.; Knox, E. R. (2006). "Contributions to the Nearby Stars (NStars) Project: Spectroscopy of Stars Earlier than M0 within 40 pc--The Southern Sample". The Astronomical Journal. 132 (1): 161–170. arXiv:astro-ph/0603770. Bibcode:2006AJ....132..161G. doi:10.1086/504637. S2CID 119476992.
  4. Mallama, A. (2014). "Sloan Magnitudes for the Brightest Stars". The Journal of the American Association of Variable Star Observers. 42 (2): 443. Bibcode:2014JAVSO..42..443M.Vizier catalog entry
  5. Fuhrmann, K.; Chini, R.; Kaderhandt, L.; Chen, Z. (2017). "Multiplicity among Solar-type Stars". The Astrophysical Journal. 836 (1): 139. Bibcode:2017ApJ...836..139F. doi:10.3847/1538-4357/836/1/139.
  6. Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
  7. David, Trevor J.; Hillenbrand, Lynne A. (2015). "The Ages of Early-Type Stars: Strömgren Photometric Methods Calibrated, Validated, Tested, and Applied to Hosts and Prospective Hosts of Directly Imaged Exoplanets". The Astrophysical Journal. 804 (2): 146. arXiv:1501.03154. Bibcode:2015ApJ...804..146D. doi:10.1088/0004-637X/804/2/146. S2CID 33401607. Vizier catalog entry
  8. "ksi Oph". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2019-10-08.
  9. Eggleton, P. P.; Tokovinin, A. A. (September 2008). "A catalogue of multiplicity among bright stellar systems". Monthly Notices of the Royal Astronomical Society. 389 (2): 869–879. arXiv:0806.2878. Bibcode:2008MNRAS.389..869E. doi:10.1111/j.1365-2966.2008.13596.x. S2CID 14878976.
  10. Mason, Brian D.; et al. (200). "The 2001 US Naval Observatory Double Star CD-ROM. I. The Washington Double Star Catalog". The Astronomical Journal. 122 (6): 3466. Bibcode:2001AJ....122.3466M. doi:10.1086/323920. Vizier catalog entry
  11. Haakonsen, Christian Bernt; Rutledge, Robert E. (September 2009). "XID II: Statistical Cross-Association of ROSAT Bright Source Catalog X-ray Sources with 2MASS Point Source Catalog Near-Infrared Sources". The Astrophysical Journal Supplement. 184 (1): 138–151. arXiv:0910.3229. Bibcode:2009ApJS..184..138H. doi:10.1088/0067-0049/184/1/138. S2CID 119267456.
  12. Allen, R.H. (1899), Star Names: Their Lore and Meaning, p. 297
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