Lambda Lupi

Lambda Lupi, Latinized from λ Lupi, is a triple star[11] system in the southern constellation of Lupus. It is visible to the naked eye with a combined apparent visual magnitude of 4.04.[2] Based upon an annual parallax shift of just 4.20[1] mas as seen from Earth, it is located roughly 800 light years from the Sun. The system has a peculiar velocity of 27.4±4.9 km/s relative to its neighbors, making it a candidate runaway star system.[9] It is a member of the Upper-Centaurus Lupus sub-group in the Scorpius-Centaurus OB association.[12]

Lambda Lupi
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Lupus
Right ascension  15h 08m 50.61639s[1]
Declination −45° 16′ 47.4950″[1]
Apparent magnitude (V) 4.04[2] (4.43 + 5.23)[3]
Characteristics
Spectral type B3 V[4] (B3 V + B3 V)[5]
U−B color index −0.67[2]
B−V color index −0.18[2]
Astrometry
Radial velocity (Rv)+9.80±1.78[6] km/s
Proper motion (μ) RA: −15.88[1] mas/yr
Dec.: −26.80[1] mas/yr
Parallax (π)4.20 ± 0.66[1] mas
Distanceapprox. 800 ly
(approx. 240 pc)
Absolute magnitude (MV)−2.75[7]
Orbit[8]
Period (P)70.8±0.8 yr
Semi-major axis (a)0.2597±0.0021″
Eccentricity (e)0.6283±0.0090
Inclination (i)71.59±0.41°
Longitude of the node (Ω)26.64±0.61°
Periastron epoch (T)1997.907 ± 0.105
Argument of periastron (ω)
(secondary)		299.9±1.1°
Details
λ Lup A
Mass8.14[8] M☉
Rotational velocity (v sin i)135 km/s
Age28.1±4.1[9] Myr
λ Lup B
Mass5.84 M☉
Other designations
λ Lup, CD−44° 9889, HD 133955, HIP 74117, HR 5626, SAO 225483, WDS J15088-4517AB.[10]
Database references
SIMBADdata

The two visible components of this system orbit each other over a period of 70.8 years with a large eccentricity of 0.63.[8] The primary component has a visual magnitude of 4.43, while the secondary is of magnitude 5.23.[3] Both are B-type main sequence stars with a stellar classification of B3 V.[5] One of the pair is itself a double-lined spectroscopic binary, making this a triple star system.[11]

References
  1. 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.
  2. Mermilliod, J.-C. (1986), "Compilation of Eggen's UBV data, transformed to UBV (unpublished)", Catalogue of Eggen's UBV Data, SIMBAD, Bibcode:1986EgUBV........0M.
  3. Eggleton, P. P.; Tokovinin, A. A. (September 2008), "A catalogue of multiplicity among bright stellar systems", Monthly Notices of the Royal Astronomical Society, 389 (2): 869–879, arXiv:0806.2878, Bibcode:2008MNRAS.389..869E, doi:10.1111/j.1365-2966.2008.13596.x.
  4. Houk, Nancy (1978), Michigan catalogue of two-dimensional spectral types for the HD stars, 2, Ann Arbor: Dept. of Astronomy, University of Michigan, Bibcode:1978mcts.book.....H.
  5. Edwards, T. W. (April 1976), "MK classification for visual binary components", Astronomical Journal, 81: 245–249, Bibcode:1976AJ.....81..245E, doi:10.1086/111879. The system is listed in Table II as −44°9889.
  6. de Bruijne, J. H. J.; Eilers, A.-C. (October 2012), "Radial velocities for the HIPPARCOS-Gaia Hundred-Thousand-Proper-Motion project", Astronomy & Astrophysics, 546: 14, arXiv:1208.3048, Bibcode:2012A&A...546A..61D, doi:10.1051/0004-6361/201219219, A61.
  7. 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.
  8. Tokovinin, Andrei (2012), "Speckle Interferometry and Orbits of "Fast" Visual Binaries", The Astronomical Journal, 144 (2), 56, arXiv:1206.1882, Bibcode:2012AJ....144...56T, doi:10.1088/0004-6256/144/2/56.
  9. Tetzlaff, N.; et al. (January 2011), "A catalogue of young runaway Hipparcos stars within 3 kpc from the Sun", Monthly Notices of the Royal Astronomical Society, 410 (1): 190–200, arXiv:1007.4883, Bibcode:2011MNRAS.410..190T, doi:10.1111/j.1365-2966.2010.17434.x.
  10. "* lam Lup". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2017-03-07.
  11. Nitschelm, C. (December 2004), "Discovery and confirmation of some double-lined spectroscopic binaries in the Sco-Cen Complex", in Hilditch, R. W.; Hensberge, H.; Pavlovski, K. (eds.), In Spectroscopically and Spatially Resolving the Components of the Close Binary Stars, Proceedings of the Workshop held 20-24 October 2003 in Dubrovnik, Croatia, ASP Conference Series, 318, San Francisco: Astronomical Society of the Pacific, pp. 291–293, Bibcode:2004ASPC..318..291N.
  12. Wolff, S. C.; et al. (2007), "Rotational Velocities for B0-B3 Stars in Seven Young Clusters: Further Study of the Relationship between Rotation Speed and Density in Star-Forming Regions", The Astronomical Journal, 133 (3): 1092–1103, arXiv:astro-ph/0702133, Bibcode:2007AJ....133.1092W, doi:10.1086/511002.
  • Kaler, James B. (June 20, 2014), "Lambda Lupi", Stars, University of Illinois, retrieved 2017-03-08.
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