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 (A) + 5.22 (B) + 11.0 (C))[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]
PrimaryA
CompanionB
Period (P)192 yr
Semi-major axis (a)0.91″[7]
(47.8 AU)[8]
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°
Orbit[8]
PrimaryAa
CompanionAb
Period (P)1 month
Semi-major axis (a)0.32 astronomical unit|AU
Details[8]
Aa
Mass2.39 M☉
Radius2.45 R☉
Luminosity76.0+5.1
−4.8[9] L☉
Temperature9,550 K
Rotational velocity (v sin i)138[9] km/s
Ab
Mass1.62 M☉
Radius1.56 R☉
Temperature7,710 K
B
Mass1.82 M☉
Radius1.73 R☉
Temperature8,330 K
C
Mass0.62 M☉
Radius0.58[10] R☉
Luminosity0.09[10] L☉
Temperature4,157[10] K
Other designations
λ Oph, 10 Oph, NSV 7784, BD+02°3118, HD 148857, HIP 80883, HR 6149, SAO 121658, ADS 10087, WDS 16309+0159[11]
Database references
SIMBADdata

λ Ophiuchi, Latinized as Lambda Ophiuchi, is a quadruple star system[8] in the equatorial constellation of Ophiuchus. It has the traditional name Marfik /ˈmɑːrfɪk/,[12] which now applies exclusively to the primary component.[13] 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 system can be divided in three pairs and is in a hierarchical architecture, with orbits inside others. The inner pair is made up of the components Aa and Ab, which take about one month to complete an orbit around each other and are separated by 0.32 astronomical units.[8] It has a combined visual magnitude of 4.18.[3] The primary is an A-type main-sequence star, with a class of A0V, indicating that it is generating energy through core hydrogen fusion.[4] It has about 2.45 times the Sun's radius and an effective temperature of 9,550 K,[8] giving it the blue-white hue typical of early A-type stars.[14] The secondary is slightly cooler and smaller, with 1.56 times the Sun's radius and an effective temperature of 7,710 K.[8] This temperature is close to the dividing line between F and A-type stars and give it a white hue.[14]

The A-B system has an orbital period of 192 years, a physical separation of 48 AU and an eccentricity of 0.611.[7][8] The secondary, component B, of magnitude 5.22,[3] is also an A-type main-sequence star, with a spectral class A4V.[4] It is 1.73 times as large as the Sun and has an effective temperature of 8,330 K,[8] giving it the white hue of A-type stars.[14]

Component C is magnitude 11.0 and lies at an angular separation of 119″ from the A-B pair,[3] translating to 6,370 astronomical units at its distance.[8] It has a common proper motion and is at approximately the same distance as the other two stars,[10] although any orbit would last for hundreds of thousands of years.[15] It has a mass 62% of the Sun's,[8] a radius 58% of the Sun's, a temperature of about 4,157 K, and 9% of the Sun's luminosity.[10] It has an estimated spectral type of K6.[15]

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).[16]

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)[17] to catalogue and standardize proper names for stars. The WGSN decided to attribute proper names to individual stars rather than entire multiple systems.[18] 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.[13]

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 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 7.2 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. ↑ 8.00 8.01 8.02 8.03 8.04 8.05 8.06 8.07 8.08 8.09 8.10 Waisberg, Idel; Klein, Ygal; Katz, Boaz (2023-06-05). "Hidden Companions to Intermediate-mass Stars. V. Discovery of a 1.6 M☉, 0.3 au Companion to Marfik within the 48 au Visual Binary HIP 80883 = λ Ophiuchi". Research Notes of the AAS 7 (6): 114. doi:10.3847/2515-5172/acda9d. ISSN 2515-5172. Bibcode: 2023RNAAS...7..114W. 
  9. ↑ 9.0 9.1 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. 
  10. ↑ 10.0 10.1 10.2 10.3 10.4 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.
  11. ↑ "lam Oph". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=lam+Oph. 
  12. ↑ 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. 
  13. ↑ 13.0 13.1 "Naming Stars". IAU.org. https://www.iau.org/public/themes/naming_stars/. Retrieved 16 December 2017. 
  14. ↑ 14.0 14.1 14.2 "The Colour of Stars". Australia Telescope, Outreach and Education. Commonwealth Scientific and Industrial Research Organisation. December 21, 2004. http://outreach.atnf.csiro.au/education/senior/astrophysics/photometry_colour.html. Retrieved 2012-01-16. 
  15. ↑ 15.0 15.1 A. Tokovinin. "HR 6149". http://www.ctio.noao.edu/~atokovin/stars/stars.php?cat=HR&number=6149. 
  16. ↑ Hessman, F. V.; et al. (2010). "On the naming convention used for multiple star systems and extrasolar planets". arXiv:1012.0707 [astro-ph.SR].
  17. ↑ IAU Working Group on Star Names (WGSN), International Astronomical Union, https://www.iau.org/science/scientific_bodies/working_groups/280/, retrieved 22 May 2016. 
  18. ↑ "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. 



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