Lambda Ophiuchi
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]
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| 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 mas[1] |
| Distance | 173 ± 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 | |
| Mass | 2.62±0.04[8] M☉ |
| Luminosity | 76.0+5.1 −4.8[8] L☉ |
| Temperature | 8,831+101 −102[8] K |
| Rotational velocity (v sin i) | 138[8] km/s |
| B | |
| Mass | 1.90[9] M☉ |
| C | |
| Mass | 0.72[9] M☉ |
| Other designations | |
| Database references | |
| SIMBAD | data |
System edit
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 edit
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 edit
- ^ a b c d e f Van Leeuwen, F. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics. 474 (2): 653–664. arXiv:0708.1752. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357. S2CID 18759600.
- ^ a b c d e f Anderson, E.; Francis, Ch. (2012). "XHIP: An extended hipparcos compilation". Astronomy Letters. 38 (5): 331. arXiv:1108.4971. Bibcode:2012AstL...38..331A. doi:10.1134/S1063773712050015. S2CID 119257644.
- ^ a b c d e 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. arXiv:0806.2878. Bibcode:2008MNRAS.389..869E. doi:10.1111/j.1365-2966.2008.13596.x. S2CID 14878976.
- ^ a b c Edwards, T. W. (1976). "MK classification for visual binary components". The Astronomical Journal. 81: 245. Bibcode:1976AJ.....81..245E. doi:10.1086/111879.
- ^ Johnson, H. L.; et al. (1966). "UBVRIJKL photometry of the bright stars". Communications of the Lunar and Planetary Laboratory. 4 (99): 99. Bibcode:1966CoLPL...4...99J.
- ^ Samus, N. N.; et al. (2017). "General Catalogue of Variable Stars". Astronomy Reports. 5.1. 61 (1): 80–88. Bibcode:2017ARep...61...80S. doi:10.1134/S1063772917010085. S2CID 125853869.
- ^ 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. S2CID 121998591.
- ^ a b c d Zorec, J.; et al. (2012). "Rotational velocities of A-type stars. IV. Evolution of rotational velocities". Astronomy and Astrophysics. 537: A120. arXiv:1201.2052. Bibcode:2012A&A...537A.120Z. doi:10.1051/0004-6361/201117691. S2CID 55586789.
- ^ a b c d A. Tokovinin. "HR 6149". Multiple Star Catalogue.
- ^ a b "lam Oph". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2019-09-20.
- ^ 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.
- ^ a b "Naming Stars". IAU.org. Retrieved 16 December 2017.
- ^ 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. S2CID 14376211.
- ^ a b Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
- ^ Hessman, F. V.; et al. (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.