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] |
Characteristics | |
Spectral type | A0V+[2] |
U−B color index | +0.01[3] |
B−V color index | +0.01[3] |
Variable type | Suspected |
Astrometry | |
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) |
Orbit[5] | |
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) (secondary) | 157.5° |
Details | |
Rotational velocity (v sin i) | 138[6] km/s |
Other designations | |
Database references | |
SIMBAD | data |
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 (also named Marfik[8]) and B.
Nomenclature
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).[9]
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)[10] to catalogue and standardize proper names for stars. The WGSN decided to attribute proper names to individual stars rather than entire multiple systems.[11] 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.[8]
Properties
Lambda Ophiuchi has apparent magnitude +3.82. Its to spectral type is A1V+A. The two components orbit each other with an period of 129 years.[5]
References
- 1 2 3 4 Perryman, M. A. C.; et al. (April 1997). "The HIPPARCOS Catalogue". Astronomy & Astrophysics. 323: L49–L52. Bibcode:1997A&A...323L..49P.
- 1 2 3 "lam Oph -- Variable Star". SIMBAD. Centre de Données astronomiques de Strasbourg. Retrieved 8 June 2010.
- 1 2 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.
- ↑ 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.
- 1 2 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.
- ↑ 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.
- ↑ 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.
- 1 2 "Naming Stars". IAU.org. Retrieved 16 December 2017.
- ↑ 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].
- ↑ IAU Working Group on Star Names (WGSN), International Astronomical Union, retrieved 22 May 2016.
- ↑ "WG Triennial Report (2015-2018) - Star Names" (PDF). p. 5. Retrieved 2018-07-14.
External links