Lambda Ophiuchi

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Lambda Ophiuchi
Observation data
Epoch J2000      Equinox J2000
Constellation Ophiuchus
Right ascension  16h 30m 54.8229s[1]
Declination +01° 59′ 02.123″[1]
Apparent magnitude (V) 3.90[2]
Spectral type A0V+[2]
U−B color index +0.01[3]
B−V color index +0.01[3]
Variable type Suspected
Radial velocity (Rv)–13.5[4] km/s
Proper motion (μ) RA: –31.37 mas/yr
Dec.: –73.00 mas/yr
Parallax (π)19.63 ± 1.34[1] mas
Distance170 ± 10 ly
(51 ± 3 pc)
Period (P)192 yr
Semi-major axis (a)0.91″
Eccentricity (e)0.611
Inclination (i)23.0°
Longitude of the node (Ω)53.3°
Periastron epoch (T)B 1939.7
Argument of periastron (ω)
Rotational velocity (v sin i)138[6] km/s
Other designations
λ Oph, 10 Oph, HR 6149, BD+02° 3118, HD 148857, SAO 121658, HIP 80883, WDS 16309+0159.[2]
Database references

Lambda Ophiuchi (λ Ophiuchi, abbreviated Lambda Oph, λ Oph) is a triple star system in the constellation of Ophiuchus. It is approximately 170 light-years from the Sun, based on its parallax.[1]

The system consists of a binary pair,[7] designated Lambda Ophiuchi AB, together with a third companion, C. AB's two components are themselves designated Lambda Ophiuchi A (officially named Marfik /ˈmɑːrfɪk/, the traditional name for the system)[8][9]) and B.


λ Ophiuchi (Latinised to Lambda Ophiuchi) is the system's Bayer designation. The designations of the three components as Lambda Ophiuchi A, B and C derive from the convention used by the Washington Multiplicity Catalog (WMC) for multiple star systems, and adopted by the International Astronomical Union (IAU).[10]

It bore the traditional name Marfik (or Marsik), from the Arabic مرفق marfiq "elbow". In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN)[11] to catalogue and standardize proper names for stars. The WGSN decided to attribute proper names to individual stars rather than entire multiple systems.[12] It approved the name Marfik for the component Lambda Ophiuchi A on 12 September 2016 and it is now so included in the List of IAU-approved Star Names.[9]


Lambda Ophiuchi has apparent magnitude +3.82. Its to spectral type is A1V+A. The two components orbit each other with a period of 129 years.[5]


  1. ^ a b c d Perryman, M. A. C.; et al. (April 1997). "The HIPPARCOS Catalogue". Astronomy & Astrophysics. 323: L49–L52. Bibcode:1997A&A...323L..49P.
  2. ^ a b c "lam Oph – Variable Star". SIMBAD. Centre de Données astronomiques de Strasbourg. Retrieved 8 June 2010.
  3. ^ a b Johnson, H. L.; et al. (1966). "UBVRIJKL photometry of the bright stars". Communications of the Lunar and Planetary Laboratory. 4 (99). Bibcode:1966CoLPL...4...99J.
  4. ^ Evans, D. S. (June 20–24, 1966). "The Revision of the General Catalogue of Radial Velocities". In Batten, Alan Henry; Heard, John Frederick (eds.). Determination of Radial Velocities and their Applications, Proceedings from IAU Symposium no. 30. University of Toronto: International Astronomical Union. Bibcode:1967IAUS...30...57E.
  5. ^ a b Heintz, W. D.; Strom, C. (1993). "The visual binary Lambda Ophiuchi". Astronomical Society of the Pacific. 105 (685): 293. Bibcode:1993PASP..105..293H. doi:10.1086/133145.
  6. ^ Royer, F.; Zorec, J.; Gómez, A. E. (February 2007). "Rotational velocities of A-type stars. III. Velocity distributions". Astronomy and Astrophysics. 463 (2): 671–682. arXiv:astro-ph/0610785. Bibcode:2007A&A...463..671R. doi:10.1051/0004-6361:20065224.
  7. ^ Lastennet, E.; Fernandes, J.; Lejeune, Th. (June 2002). "A revised HRD for individual components of binary systems from BaSeL BVRI synthetic photometry. Influence of interstellar extinction and stellar rotation". Astronomy and Astrophysics. 388: 309–319. arXiv:astro-ph/0203341. Bibcode:2002A&A...388..309L. doi:10.1051/0004-6361:20020439.
  8. ^ Kunitzsch, Paul; Smart, Tim (2006). A Dictionary of Modern star Names: A Short Guide to 254 Star Names and Their Derivations (2nd rev. ed.). Cambridge, Massachusetts: Sky Pub. ISBN 978-1-931559-44-7.
  9. ^ a b "Naming Stars". Retrieved 16 December 2017.
  10. ^ Hessman, F. V.; Dhillon, V. S.; Winget, D. E.; Schreiber, M. R.; Horne, K.; Marsh, T. R.; Guenther, E.; Schwope, A.; Heber, U. (2010). "On the naming convention used for multiple star systems and extrasolar planets". arXiv:1012.0707 [astro-ph.SR].
  11. ^ IAU Working Group on Star Names (WGSN), International Astronomical Union, retrieved 22 May 2016.
  12. ^ "WG Triennial Report (2015–2018) – Star Names" (PDF). p. 5. Retrieved 2018-07-14.

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