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HD 134687 (e Lupi) is a binary star system in the southern constellation Lupus. It is visible to the naked eye with an apparent visual magnitude of 4.81. The distance to HD 134687 can be estimated from its annual parallax shift of 7.6 mas, yielding roughly 430 light years. It is a member of the ~11 million year old Upper Centaurus–Lupus subgroup of the Scorpius–Centaurus association, the closest OB association to the Sun.

This is a single-lined spectroscopic binary star system. The pair have a nearly circular orbit with an eccentricity of at or below 0.03 and a period of 0.901407 days (21.6338 h). The primary has an a sin i value of 2.735×10 km, which only gives a lower bound for the semimajor axis a since the orbital inclination i to the line of sight is unknown. The system is a source for X-ray emission.

The visible component has a stellar classification of B3 IV/V, matching a B-type star showing a spectrum with mixed traits of a main sequence and a subgiant star. It is 20 million years old with a projected rotational velocity of 13 km/s. The star has 6.0 times the mass of the Sun and 7.1 times the Sun's radius. It is radiating 997 times the Sun's luminosity from its photosphere at an effective temperature of 17,100 K.

References

1. ^ 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.
2. ^ Hohle, M. M.; Neuhäuser, R.; Schutz, B. F. (April 2010), "Masses and luminosities of O- and B-type stars and red supergiants", Astronomische Nachrichten, 331 (4): 349, arXiv:1003.2335, Bibcode:2010AN....331..349H, doi:10.1002/asna.200911355, S2CID 111387483.
3. ^ Houk, Nancy (1978), Michigan catalogue of two-dimensional spectral types for the HD stars, vol. 2, Ann Arbor: Dept. of Astronomy, University of Michigan, Bibcode:1978mcts.book.....H.
4. ^ 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.
5. 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, S2CID 59451347, A61.
6. ^ Buscombe, W.; Kennedy, P. M. (August 1962), "Two B-Type Spectroscopic Binaries", Publications of the Astronomical Society of the Pacific, 74 (439): 323, Bibcode:1962PASP...74..323B, doi:10.1086/127818
7. ^ 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, S2CID 118629873.
8. ^ Pasinetti Fracassini, L. E.; et al. (February 2001), "Catalogue of Apparent Diameters and Absolute Radii of Stars (CADARS)", Astronomy and Astrophysics, 367 (2) (Third ed.): 521–524, arXiv:astro-ph/0012289, Bibcode:2001A&A...367..521P, doi:10.1051/0004-6361:20000451, S2CID 425754.
9. ^ Wolff, S. C.; Strom, S. E.; Dror, D.; Venn, K. (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, S2CID 119074863.
10. "HD 134687". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2018-07-22.
11. Chen, Christine H.; et al. (September 2012), "A Spitzer MIPS Study of 2.5-2.0 M_⊙ Stars in Scorpius–Centaurus", The Astrophysical Journal, 756 (2): 24, arXiv:1207.3415, Bibcode:2012ApJ...756..133C, doi:10.1088/0004-637X/756/2/133, S2CID 119278056, 133.
12. Berghoefer, T. W.; Schmitt, J. H. M. M.; Cassinelli, J. P. (September 1996), "The ROSAT all-sky survey catalogue of optically bright OB-type stars", Astronomy and Astrophysics Supplement, 118 (3): 481–494, Bibcode:1996A&AS..118..481B, doi:10.1051/aas:1996213.

v t e Constellation of Lupus
List of stars in Lupus Lupus in Chinese astronomy
Stars	Bayer α β γ δ ε ζ η θ ι κ κ λ μ ν ν ξ ξ ο π ρ σ τ τ υ φ φ χ ψ ψ ω Flamsteed 1 (i) 2 (f) Variable RU EX GG GQ HR II IL IM KT (d) V407 HR 5364 5401 5651 (e) 5724 (k) 5825 (g) 5943 5967 HD 134004 142527 Other Gliese 588 HIP 70849 Lupus-TR-3 SAO 206462 SSSPM J1549-3544 WASP-132
Exoplanets GQ Lupi b HIP 70849 b Lupus-TR-3b WASP-178b
Star clusters NGC 5749 NGC 5822 NGC 5824 NGC 5927 NGC 5986
Nebulae IC 4406 NGC 5882
Galaxies NGC 5643
Category

• B-type subgiants
• Spectroscopic binaries
• Lupus (constellation)
• Bayer objects
• Durchmusterung objects
• Henry Draper Catalogue objects
• Hipparcos objects
• Bright Star Catalogue objects
• Upper Centaurus Lupus