Omicron_Hydrae

Omicron Hydrae

Omicron Hydrae

Blue-hued star in the constellation Hydra

Omicron Hydrae (ο Hya) is the Bayer designation for a solitary[8] star in the equatorial constellation Hydra. At one time it bore the Flamsteed designation 25 Crateris, but this is no longer used by astronomers so as to avoid confusion.[9] With an apparent visual magnitude of 4.70,[2] this star is visible to the naked eye. Based upon an annual parallax shift of 7.27 mas,[1] it is located around 449 light years from the Sun.

Quick Facts Constellation, Right ascension ...

This is a B-type main sequence star with a stellar classification of B9 V.[3] It has completed an estimated 98.4%±1.1% of its lifetime on the main sequence. With 3.56[6] times the mass of the Sun, it radiates 309 times the Sun's luminosity from its outer atmosphere at an effective temperature of 10,495 K.[6] The rate of spin is relatively high, with a projected rotational velocity of 160 km/s.[6]

References

  1. [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, S2CID 18759600.
  2. [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    Mermilliod, J.-C. (1986), "Compilation of Eggen's UBV data, transformed to UBV (unpublished)", Catalogue of Eggen's UBV Data, SIMBAD, Bibcode:1986EgUBV........0M.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. [3]
    Houk, N. (1982), Michigan Catalogue of Two-dimensional Spectral Types for the HD stars, vol. 3, Ann Arbor, MI: Department of Astronomy, University of Michigan, Bibcode:1982mcts.book.....H.
  4. [4]
    Wielen, R.; et al. (2000), "Sixth Catalogue of Fundamental Stars (FK6). Part III. Additional fundamental stars with direct solutions", Veröffentlichungen Astronomisches Rechen-Institut Heidelberg, vol. 37, no. 37, Karlsruhe: Verlag G. Braun, pp. 1–308, Bibcode:2000VeARI..37....1W, ISBN 3-7650-0536-3.
  5. [5]
    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.
  6. [6]
    Zorec, J.; Royer, F. (January 2012), "Rotational velocities of A-type stars. IV. Evolution of rotational velocities", Astronomy & Astrophysics, 537: A120, arXiv:1201.2052, Bibcode:2012A&A...537A.120Z, doi:10.1051/0004-6361/201117691, S2CID 55586789.
  7. [7]
    "* omi Hya". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2017-01-06.
  8. [8]
    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.
  9. [9]
    Wagman, M. (August 1987), "Flamsteed's Missing Stars", Journal for the History of Astronomy, 18 (3): 216, Bibcode:1987JHA....18..209W, doi:10.1177/002182868701800305, S2CID 118445625.
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