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
Distance 170 ± 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.[2]
Database references

Lambda Ophiuchi (λ Ophiuchi, abbreviated Lambda Oph, λ Oph), also named Marfik,[7] is a binary star[8] in the constellation of Ophiuchus. It is approximately 170 light years from Earth, based on its parallax.[1]


λ Ophiuchi (Latinised to Lambda Ophiuchi) is the system's Bayer designation.

It bore the traditional name Marfik (or Marsik), meaning "the elbow" in Arabic. In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN)[9] to catalogue and standardize proper names for stars. The WGSN approved the name Marfik for this star on 12 September 2016 and it is now so entered in the IAU Catalog of Star Names.[7]


Lambda Ophiuchi has apparent magnitude +3.82. Its to spectral type is A1V+A. The two components orbit each other with an orbital 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. 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/0610785Freely accessible. Bibcode:2007A&A...463..671R. doi:10.1051/0004-6361:20065224. 
  7. ^ a b "IAU Catalog of Star Names". Retrieved 28 July 2016. 
  8. ^ 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/0203341Freely accessible. Bibcode:2002A&A...388..309L. doi:10.1051/0004-6361:20020439. 
  9. ^ IAU Working Group on Star Names (WGSN), International Astronomical Union, retrieved 22 May 2016. 

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