Astronomy:Lambda Ophiuchi

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Short description: Star system in the constellation Ophiuchus
Lambda Ophiuchi
Observation data
Equinox J2000.0]] (ICRS)
Constellation Ophiuchus
Right ascension  16h 30m 54.82314s[1]
Declination +01° 59′ 02.1209″[1]
Apparent magnitude (V) 3.82[2] 4.18 + 5.22 + 11.0)[3]
Characteristics
Spectral type A0V + A4V[4]
U−B color index +0.01[5]
B−V color index +0.022±0.014[2]
Variable type Suspected[6]
Astrometry
Radial velocity (Rv)−16.0±1.5[2] km/s
Proper motion (μ) RA: –30.98[1] mas/yr
Dec.: –73.42[1] mas/yr
Parallax (π)18.84 ± 0.55[1] mas
Distance173 ± 5 ly
(53 ± 2 pc)
Absolute magnitude (MV)0.20[2]
Orbit[7]
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
A
Mass2.62±0.04[8] M☉
Luminosity76.0+5.1
−4.8[8] L☉
Temperature8,831+101
−102[8] K
Rotational velocity (v sin i)138[8] km/s
B
Mass1.90[9] M☉
C
Mass0.72[9] M☉
Other designations
λ Oph, 10 Oph, NSV 7784, BD+02°3118, HD 148857, HIP 80883, HR 6149, SAO 121658, ADS 10087, WDS 16309+0159[10]
Database references
SIMBADdata

λ Ophiuchi, Latinized as Lambda Ophiuchi, is a triple star system[3] in the equatorial constellation of Ophiuchus.[10] It has the traditional name Marfik /ˈmɑːrfɪk/,[11] which now applies exclusively to the primary component.[12] The system is visible to the naked eye as a faint point of light with an apparent visual magnitude of 3.82.[2] It is located approximately 173 light-years from the Sun, based on its parallax,[1] but is drifting closer with a radial velocity of –16 km/s.[2]

System

The inner pair form a binary star[13] system with an orbital period of 192 years and an eccentricity of 0.611.[7] Both components are A-type main-sequence stars, indicating that they are generating energy through core hydrogen fusion. The brighter member of this pair, designated component A, is the primary for the system with a visual magnitude of 4.18[3] and a stellar classification of A0V.[4] The secondary, component B, is magnitude 5.22[3] and class A4V.[4]

Component C is magnitude 11.0 and lies at an angular separation of 119″ from the inner pair.[3] It has a common proper motion and is at approximately the same distance as the other two stars,[14] although any orbit would last for hundreds of thousands of years.[9] It has a mass 72% of the Sun's, a radius 58% of the Sun's, a temperature of about 4,157 K, and 7% of the Sun's luminosity.[14] It has an estimated spectral type of K6.[9]

Nomenclature

λ 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).[15]

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)[16] to catalogue and standardize proper names for stars. The WGSN decided to attribute proper names to individual stars rather than entire multiple systems.[17] 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.[12]

References

  1. ↑ 1.0 1.1 1.2 1.3 1.4 1.5 Van Leeuwen, F. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics 474 (2): 653–664. doi:10.1051/0004-6361:20078357. Bibcode: 2007A&A...474..653V. 
  2. ↑ 2.0 2.1 2.2 2.3 2.4 2.5 Anderson, E.; Francis, Ch. (2012). "XHIP: An extended hipparcos compilation". Astronomy Letters 38 (5): 331. doi:10.1134/S1063773712050015. Bibcode: 2012AstL...38..331A. 
  3. ↑ 3.0 3.1 3.2 3.3 3.4 Eggleton, P. P.; Tokovinin, A. A. (2008). "A catalogue of multiplicity among bright stellar systems". Monthly Notices of the Royal Astronomical Society 389 (2): 869. doi:10.1111/j.1365-2966.2008.13596.x. Bibcode: 2008MNRAS.389..869E. 
  4. ↑ 4.0 4.1 4.2 Edwards, T. W. (1976). "MK classification for visual binary components". The Astronomical Journal 81: 245. doi:10.1086/111879. Bibcode: 1976AJ.....81..245E. 
  5. ↑ Johnson, H. L. (1966). "UBVRIJKL photometry of the bright stars". Communications of the Lunar and Planetary Laboratory 4 (99): 99. Bibcode: 1966CoLPL...4...99J. 
  6. ↑ Samus, N. N. et al. (2017). "General Catalogue of Variable Stars". Astronomy Reports. 5.1 61 (1): 80–88. doi:10.1134/S1063772917010085. Bibcode: 2017ARep...61...80S. 
  7. ↑ 7.0 7.1 Heintz, W. D.; Strom, C. (1993). "The visual binary Lambda Ophiuchi". Astronomical Society of the Pacific 105 (685): 293. doi:10.1086/133145. Bibcode: 1993PASP..105..293H. 
  8. ↑ 8.0 8.1 8.2 8.3 Zorec, J. et al. (2012). "Rotational velocities of A-type stars. IV. Evolution of rotational velocities". Astronomy and Astrophysics 537: A120. doi:10.1051/0004-6361/201117691. Bibcode: 2012A&A...537A.120Z. 
  9. ↑ 9.0 9.1 9.2 9.3 A. Tokovinin. "HR 6149". http://www.ctio.noao.edu/~atokovin/stars/stars.php?cat=HR&number=6149. 
  10. ↑ 10.0 10.1 "lam Oph". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=lam+Oph. 
  11. ↑ 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. 
  12. ↑ 12.0 12.1 "Naming Stars". IAU.org. https://www.iau.org/public/themes/naming_stars/. Retrieved 16 December 2017. 
  13. ↑ 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. doi:10.1051/0004-6361:20020439. Bibcode: 2002A&A...388..309L. 
  14. ↑ 14.0 14.1 Brown, A. G. A. (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics 616: A1. doi:10.1051/0004-6361/201833051. Bibcode: 2018A&A...616A...1G.  Gaia DR2 record for this source at VizieR.
  15. ↑ Hessman, F. V.; et al. (2010). "On the naming convention used for multiple star systems and extrasolar planets". arXiv:1012.0707 [astro-ph.SR].
  16. ↑ IAU Working Group on Star Names (WGSN), International Astronomical Union, https://www.iau.org/science/scientific_bodies/working_groups/280/, retrieved 22 May 2016. 
  17. ↑ "WG Triennial Report (2015–2018) – Star Names". p. 5. https://www.iau.org/static/science/scientific_bodies/working_groups/280/wg-starnames-triennial-report-2015-2018.pdf. Retrieved 2018-07-14. 

External links



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