Article · Wikipedia archive · Last revised Jun 21, 2026

41 Ophiuchi

41 Ophiuchi is a binary star system in the zodiac constellation of Ophiuchus, and is positioned less than half a degree to the south of the celestial equator. It is visible to the naked eye as a faint, orange-hued point of light with a combined apparent visual magnitude of 4.72. The distance to this system is approximately 202 light years based on parallax.

Last revised
Jun 21, 2026
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41 Ophiuchi
Location of 41 Ophiuchi (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Ophiuchus
Right ascension 17h 16m 36.68653s1
Declination −00° 26′ 43.0915″1
Apparent magnitude (V) 4.722
(4.92 + 7.51)3
Characteristics
Evolutionary stage horizontal branch4
Spectral type K2III5
U−B color index +1.116
B−V color index +1.156
Astrometry
Radial velocity (Rv)−0.167 km/s
Proper motion (μ) RA: −31.6451 mas/yr
Dec.: −57.1441 mas/yr
Parallax (π)16.1517±0.2358 mas1
Distance202 ± 3 ly
(61.9 ± 0.9 pc)
Absolute magnitude (MV)0.722
Orbit8
Period (P)140.76±0.23 yr
Semi-major axis (a)0.959±0.008″
Eccentricity (e)0.866±0.003
Inclination (i)65.1±0.0°
Longitude of the node (Ω)220.5±0.0°
Periastron epoch (T)1890.53±0.36 B
Argument of periastron (ω)
(secondary)		287.5±0.0°
Details
41 Oph A
Mass1.469 M☉
Radius11.80+0.27
−0.391 R☉
Luminosity60.3±1.01 L☉
Surface gravity (log g)2.4210 cgs
Temperature4,509±659 K
Metallicity [Fe/H]+0.062 dex
Rotational velocity (v sin i)2.67 km/s
Age3.739 Gyr
Other designations
41 Oph, BD−00°3255, GC 23320, HD 156266, HIP 84514, HR 6415, SAO 141586, CCDM J17166-0027AB, WDS J17166-002711
Database references
SIMBADdata

41 Ophiuchi is a binary star8 system in the zodiac constellation of Ophiuchus, and is positioned less than half a degree to the south of the celestial equator. It is visible to the naked eye as a faint, orange-hued point of light with a combined apparent visual magnitude of 4.72.2 The distance to this system is approximately 202 light years based on parallax.12

This is a visual binary with an orbital period of 141 years and an eccentricity of 0.866.8 The magnitude 4.923 primary, designated component A, is an aging K-type giant star with a stellar classification of K2III.5 It is a red clump giant,4 which indicates it is on the horizontal branch and is generating energy through helium fusion at its core. The star is 3.79 billion years old with 1.469 times the mass of the Sun and has expanded to nearly 121 times the Sun's radius. It is radiating 601 times the Sun's luminosity from its swollen photosphere at an effective temperature of 4,509 K.9

The secondary companion, component B, has a visual magnitude of 7.51 and an angular separation of 0.70″ from the primary along a position angle of 22°, as of 2017.3

References

References

  1. 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.
  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. 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
  4. Alves, David R. (August 2000). "K-Band Calibration of the Red Clump Luminosity". The Astrophysical Journal. 539 (2): 732–741. arXiv:astro-ph/0003329. Bibcode:2000ApJ...539..732A. doi:10.1086/309278. S2CID 16673121.
  5. 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.
  6. 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
  7. Massarotti, Alessandro; et al. (2008). "Rotational and Radial Velocities for a Sample of 761 Hipparcos Giants and the Role of Binarity". The Astronomical Journal. 135 (1): 209–231. Bibcode:2008AJ....135..209M. doi:10.1088/0004-6256/135/1/209.
  8. Tokovinin, Andrei; et al. (August 2015). "Speckle Interferometry at SOAR in 2014". The Astronomical Journal. 150 (2): 17. arXiv:1506.05718. Bibcode:2015AJ....150...50T. doi:10.1088/0004-6256/150/2/50. S2CID 30737411. 50.
  9. Luck, R. Earle (2015), "Abundances in the Local Region. I. G and K Giants", Astronomical Journal, 150 (3), 88, arXiv:1507.01466, Bibcode:2015AJ....150...88L, doi:10.1088/0004-6256/150/3/88, S2CID 118505114.
  10. Allende Prieto, C.; Lambert, D. L. (1999). "Fundamental parameters of nearby stars from the comparison with evolutionary calculations: Masses, radii and effective temperatures". Astronomy and Astrophysics. 352: 555–562. arXiv:astro-ph/9911002. Bibcode:1999A&A...352..555A. Vizier catalog entry
  11. "41 Oph". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2019-06-21.
  12. Van Leeuwen, F. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics. 474 (2): 653–664. arXiv:0708.1752. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357. S2CID 18759600. Vizier catalog entry