HD 119921 is a single,[4] white-hued star in the southern constellation of Centaurus. it has the Bayer designation z Centauri. This is faintly visible to the naked eye, having an apparent visual magnitude of 5.15.[1] 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.[9]

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.[8] The star is radiating around 160 times the Sun's luminosity from its photosphere at an effective temperature of 10,102 K.[7]

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.[8]

References

  1. 1 2 3 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. XHIP record for this object at VizieR.
  2. 1 2 3 4 5 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.
  3. 1 2 Houk, Nancy (1979), Michigan catalogue of two-dimensional spectral types for the HD stars, vol. 3, Ann Arbor, Michigan: Dept. of Astronomy, University of Michigan, Bibcode:1982mcts.book.....H.
  4. 1 2 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, S2CID 14878976.
  5. 1 2 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. 1 2 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.
  7. 1 2 3 4 5 6 Stassun, Keivan G.; et al. (2019), "The Revised TESS Input Catalog and Candidate Target List", The Astronomical Journal, 158 (4): 138, arXiv:1905.10694, Bibcode:2019AJ....158..138S, doi:10.3847/1538-3881/ab3467.
  8. 1 2 3 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.
  9. 1 2 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, S2CID 119108982.
  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 (6): 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.
allikas: https://en.wikipedia.org/wiki/HD_119921