Upsilon Lupi

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Upsilon Lupi
Lupus IAU.svg
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The location of Upsilon Lupi (υ) in the constellation of Lupus (shown as a red target's bullseye).
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Lupus
Right ascension 15h 24m 45.00855s[1]
Declination −39° 42′ 36.9524″[1]
Apparent magnitude (V) 5.37[2] (5.37 + 10.90)[3]
Spectral type A0p Si[4]
B−V color index −0.11[2]
Radial velocity (Rv) −7.6±2.8[5] km/s
Proper motion (μ) RA: −26.10[1] mas/yr
Dec.: −54.77[1] mas/yr
Parallax (π) 8.02 ± 0.62[1] mas
Distance 410 ± 30 ly
(125 ± 10 pc)
υ Lup A
Luminosity 113[6] L
Temperature 10,049[6] K
Rotational velocity (v sin i) 0[7] km/s
Other designations
υ Lup, CD−39° 9827, HD 136933, HIP 75439, HR 5719, SAO 206597.[8]

Upsilon Lupi (υ Lup, υ Lupi) is a star system in the southern constellation of Lupus. It is faintly visible to the naked eye with an apparent visual magnitude of 5.37.[2] Based upon an annual parallax shift of 8.02[1] mas as seen from Earth, it is located around 410 light years from the Sun. The two components of Upsilon Lupi share a common proper motion through space and most likely form a wide binary star system.[9] As of 1945, the pair had an angular separation of 1.50 arc seconds along a position angle of 40°.[3]

The brighter member, component A, is a chemically peculiar Ap star with a stellar classification of A0p Si,[4] where the 'Si' suffix indicates an abnormal abundance of silicon in the star's photosphere. A magnetic field has been detected with a quadratic field strength of (764.7±311.3)×10−4 T.[10] The star is radiating 113 times the solar luminosity from its outer atmosphere at an effective temperature of 10,049 K.[6]

The magnitude 10.9 companion star, component B, has a visual magnitude of 10.90.[3] It may be the source of the X-ray emission detected coming from these coordinates.[11]


  1. ^ a b c d e f van Leeuwen, F. (2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv:0708.1752Freely accessible, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357. 
  2. ^ a b c Corben, P. M.; Stoy, R. H. (1968), "Photoelectric Magnitudes and Colours for Bright Southern Stars", Monthly Notes of the Astronomical Society of Southern Africa, 27: 11, Bibcode:1968MNSSA..27...11C. 
  3. ^ a b c Mason, B. D.; et al. (2014), "The Washington Visual Double Star Catalog", The Astronomical Journal, 122: 3466–3471, Bibcode:2001AJ....122.3466M, doi:10.1086/323920. 
  4. ^ a b Houk, Nancy (1979), Michigan catalogue of two-dimensional spectral types for the HD stars, 3, Ann Arbor, Michigan: Dept. of Astronomy, University of Michigan, Bibcode:1982MSS...C03....0H. 
  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:1208.3048Freely accessible, Bibcode:2012A&A...546A..61D, doi:10.1051/0004-6361/201219219, A61. 
  6. ^ a b c McDonald, I.; et al. (2012), "Fundamental Parameters and Infrared Excesses of Hipparcos Stars", Monthly Notices of the Royal Astronomical Society, 427 (1): 343–57, arXiv:1208.2037Freely accessible, Bibcode:2012MNRAS.427..343M, doi:10.1111/j.1365-2966.2012.21873.x. 
  7. ^ Uesugi, Akira; Fukuda, Ichiro (1970), "Catalogue of rotational velocities of the stars", Contributions from the Institute of Astrophysics and Kwasan Observatory, University of Kyoto, 
  8. ^ "ups Lup -- Star", SIMBAD Astronomical Database, Centre de Données astronomiques de Strasbourg, retrieved 2017-03-10. 
  9. ^ 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:0806.2878Freely accessible, Bibcode:2008MNRAS.389..869E, doi:10.1111/j.1365-2966.2008.13596.x. 
  10. ^ Bychkov, V. D.; et al. (April 2009), "Catalogue of averaged stellar effective magnetic fields - II. Re-discussion of chemically peculiar A and B stars", Monthly Notices of the Royal Astronomical Society, 394 (3): 1338–1350, Bibcode:2009MNRAS.394.1338B, doi:10.1111/j.1365-2966.2008.14227.x. 
  11. ^ Schröder, C.; Schmitt, J. H. M. M. (November 2007), "X-ray emission from A-type stars", Astronomy and Astrophysics, 475 (2): 677−684, Bibcode:2007A&A...475..677S, doi:10.1051/0004-6361:20077429.