HD 119921

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HD 119921
Observation data
Epoch J2000      Equinox J2000
Constellation Centaurus
Right ascension  13h 46m 56.35149s[1]
Declination –36° 15′ 06.9563″[1]
Apparent magnitude (V) 5.15[2]
Spectral type A0 V[3][4] or B9.5 III-n[5]
Radial velocity (Rv)−9.8±2.8[6] km/s
Proper motion (μ) RA: −13.293[1] mas/yr
Dec.: −11.115[1] mas/yr
Parallax (π)7.7881 ± 0.2382[1] mas
Distance420 ± 10 ly
(128 ± 4 pc)
Absolute magnitude (MV)0.93[7]
Luminosity125.24[8] L
Temperature8,801[8] K
Rotational velocity (v sin i)220[9] km/s
Other designations
z Cen, CD−35°8995, FK5 3091, HD 119921, HIP 67244, HR 5174, SAO 204835, WDS J13469-3615A[10]
Database references

HD 119921 (Bayer designation z Centauri) is a single,[4] white-hued star in the southern constellation of Centaurus. This is faintly visible to the naked eye, having an apparent visual magnitude of 5.15.[2] It forms a wide double star with a faint, magnitude 12.50 visual companion, which is located at an angular separation of 27.20 as of 2010.[11] HD 119921 is moving closer to us with a heliocentric radial velocity of around −10 km/s,[6] and is currently located some 420±10 light year from the Sun. At that distance, the visual magnitude of this star is diminished by 0.15 from extinction due to interstellar dust.[7]

This is an A-type main-sequence star with a stellar classification of A0 V, per Houk (1979).[3] However, Gray & Garrison (1987) have it classed as B9.5 III-n, suggesting it is a more evolved giant star.[5] HD 119921 is spinning rapidly with a projected rotational velocity of 220 km/s.[9] The star is radiating around 125 times the Sun's luminosity from its photosphere at an effective temperature of 8,801 K.[8]

In 1983, Molaro et al. reported the presence of super-ionized elements (triple-ionized carbon and silicon) in the far ultraviolet spectrum of HD 119921. These anomalous features are not normally detected from a star in this temperature range.[12] Instead, these blue-shifted absorption features may originate in the local interstellar medium.[9]


  1. ^ a b c d e 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. ^ a b 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.
  3. ^ 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:1982mcts.book.....H.
  4. ^ a b 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.
  5. ^ a b Gray, R. O.; Garrison, R. F. (December 1987), "The Early A-Type Stars: Refined MK Classification, Confrontation with Stroemgren Photometry, and the Effects of Rotation", Astrophysical Journal Supplement, 65: 581, Bibcode:1987ApJS...65..581G, doi:10.1086/191237.
  6. ^ a b 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. ^ a b Gontcharov, G. A. (November 2012), "Spatial distribution and kinematics of OB stars", Astronomy Letters, 38 (11): 694–706, arXiv:1606.09028, Bibcode:2012AstL...38..694G, doi:10.1134/S1063773712110035.
  8. ^ a b c McDonald, I.; et al. (2012), "Fundamental parameters and infrared excesses of Hipparcos stars", Monthly Notices of the Royal Astronomical Society, 427: 343, arXiv:1208.2037, Bibcode:2012MNRAS.427..343M, doi:10.1111/j.1365-2966.2012.21873.x.
  9. ^ a b c Freire Ferrero, R.; et al. (February 2012), "High Ionization Species in the Nearby Interstellar Medium from an Exhaustive Analysis of the IUE INES Database", The Astronomical Journal, 143 (2): 38, Bibcode:2012AJ....143...28F, doi:10.1088/0004-6256/143/2/28, 28.
  10. ^ "HD 119921". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2018-07-06.
  11. ^ 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.
  12. ^ Molaro, P.; Morossi, C.; Ramella, M.; Franco, M. (October 1983), "Superionization in the A0 V star HD 119921", Astronomy and Astrophysics, 127 (1): L3–L4, Bibcode:1983A&A...127L...3M.