Tau Ophiuchi

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τ Ophiuchi
Ophiuchus constellation map.svg
Red circle.svg

Location of τ Ophiuchi (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Ophiuchus
Right ascension 18h 03m 04.91992s[1]
Declination −8° 10′ 49.2586″[1]
Apparent magnitude (V) 5.24 (A) / 5.94 (B) [2]
Spectral type F2V(A) / F5V (B) [2]
U−B color index +0.05 (A)[3]
B−V color index +0.38 (A)[3]
Radial velocity (Rv) -38.39[4] km/s
Proper motion (μ) RA: +15.78[1] mas/yr
Dec.: -37.79[1] mas/yr
Parallax (π) 19.48 ± 0.66[1] mas
Distance 167 ± 6 ly
(51 ± 2 pc)
Mass 1.54 (A) / 1.29 (B)[5] M
Surface gravity (log g) 4.18 (A)[6] cgs
Temperature 6,813 (A)[6] K
Other designations
BD-08°4549, CCDM J18031-0811AB, 69 Ophiuchi, HIP 88404, HD 164764+164765, HR 6733+6734, WDS J18031-0811AB
Database references

Tau Ophiuchi (τ Oph) is a multiple star in the constellation Ophiuchus, approximately 167 light years away based on parallax.[1] Its two main components are two yellow-white main sequence stars, A, of magnitude 5.24 and class F2V, and B, of magnitude 5.94 and class F5V,[2] orbiting each other with a period of 257 years and eccentricity around 0.77.[7] A is reported as a spectroscopic binary with a smaller star of 0.29 solar masses orbiting it every 186 days.[5] An additional component, C, has a separation of 100.8" and magnitude 11.28.[8]


  1. ^ a b c d e f Van Leeuwen, F. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics. 474 (2): 653. arXiv:0708.1752Freely accessible. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357.  Vizier catalog entry
  2. ^ a b c Hoffleit, D.; Warren, W. H. (1995). "VizieR Online Data Catalog: Bright Star Catalogue, 5th Revised Ed. (Hoffleit+, 1991)". VizieR On-line Data Catalog: V/50. Originally published in: 1964BS....C......0H. 5050. Bibcode:1995yCat.5050....0H. 
  3. ^ a b Mallama, A. (2014). "Sloan Magnitudes for the Brightest Stars". The Journal of the American Association of Variable Star Observers. 42: 443. Bibcode:2014JAVSO..42..443M. 
  4. ^ Pourbaix, D.; Tokovinin, A. A.; Batten, A. H.; Fekel, F. C.; Hartkopf, W. I.; Levato, H.; Morrell, N. I.; Torres, G.; Udry, S. (2004). "SB9: The ninth catalogue of spectroscopic binary orbits". Astronomy and Astrophysics. 424 (2): 727. arXiv:astro-ph/0406573Freely accessible. Bibcode:2004A&A...424..727P. doi:10.1051/0004-6361:20041213. 
  5. ^ a b Tokovinin, A. (2008). "Comparative statistics and origin of triple and quadruple stars". Monthly Notices of the Royal Astronomical Society. 389 (2): 925. Bibcode:2008MNRAS.389..925T. doi:10.1111/j.1365-2966.2008.13613.x. 
  6. ^ a b 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:1501.03154Freely accessible. Bibcode:2015ApJ...804..146D. doi:10.1088/0004-637X/804/2/146.  Vizier catalog entry
  7. ^ Malkov, O. Yu.; Tamazian, V. S.; Docobo, J. A.; Chulkov, D. A. (2012). "Dynamical masses of a selected sample of orbital binaries". Astronomy & Astrophysics. 546: A69. Bibcode:2012A&A...546A..69M. doi:10.1051/0004-6361/201219774.  Vizier catalog entry
  8. ^ Mason, Brian D.; Wycoff, Gary L.; Hartkopf, William I.; Douglass, Geoffrey G.; Worley, Charles E. (2001). "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