This article is about n Centauri. Not to be confused with η Centauri or Nu Centauri.

HD 111968, also known by the Bayer designation n Centauri, is a binary star[6] in the southern constellation of Centaurus. It is a white-hued star that is faintly visible to the naked eye with an apparent visual magnitude of +4.25.[2] The star is located at a distance of approximately 149 light years based on parallax.[1] The radial velocity of the star is poorly constrained, with an estimated value of 2.5 km/s.[2]

The primary component is classified as an A-type star but there has been disagreement about the luminosity class. A. de Vaucouleurs in 1957 found a class of III, suggesting this is an evolved giant star.[9] O. J. Eggen gave a class of V in 1962,[10] as did R. O. Gray and R. F. Garrison in 1989,[4] indicating this is a main sequence star. In 1979, N. Houk found a class of IV,[3] meaning this is a subgiant star. It is a young star, some 900 million years old, with 2.07 times the mass of the Sun.[6] It is spinning with a projected rotational velocity of 92 km/s.[5] The star is 3.3 times larger than the Sun,[6] radiating 34[2] times the luminosity of the Sun from its photosphere at an effective temperature of 7,400 K.[6]

The secondary component is a K-type dwarf, still in the main sequence. It has 88% of the mass and 80% of the radius of the Sun, with an effective temperature of 5,300 K. It is separated by 26 astronomical units from the primary, taking 80 years to complete an orbit around the system's center of mass. It is likely responsible for the X-ray emission coming from the system.[6]

Once the primary component start to evolve, it will lose mass, becoming a white dwarf with a mass of 0.7 M☉, and the orbital distance will be two times wider.[6]

References

  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:0708.1752, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357, S2CID 18759600. Vizier catalog entry
  2. ^ a b c d e f 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.
  3. ^ a b 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. ^ a b Gray, R. O.; Garrison, R. F. (1989), "The Late A-Type Stars: Refined MK Classification, Confrontation with Stroemgren Photometry, and the Effects of Rotation", The Astrophysical Journal Supplement Series, 70: 623, Bibcode:1989ApJS...70..623G, doi:10.1086/191349.
  5. ^ a b c Ammler-von Eiff, Matthias; Reiners, Ansgar (June 2012), "New measurements of rotation and differential rotation in A-F stars: are there two populations of differentially rotating stars?", Astronomy & Astrophysics, 542: A116, arXiv:1204.2459, Bibcode:2012A&A...542A.116A, doi:10.1051/0004-6361/201118724, S2CID 53666672.
  6. ^ a b c d e f g h i j k l m n o Waisberg, Idel; Klein, Ygal; Katz, Boaz (April 2024), "Hidden Companions to Intermediate-mass Stars. XVIII. Discovery of a 0.88 M☉, 26 au Companion to n Centauri", Research Notes of the AAS, 8 (4): 106, Bibcode:2024RNAAS...8..106W, doi:10.3847/2515-5172/ad40a8, ISSN 2515-5172
  7. ^ David, Trevor J.; Hillenbrand, Lynne A. (2015), "The Ages of Early-Type Stars: Strömgren Photometric Methods Calibrated, Validated, Tested, and Applied to Hosts and Prospective Hosts of Directly Imaged Exoplanets", The Astrophysical Journal, 804 (2): 146, arXiv:1501.03154, Bibcode:2015ApJ...804..146D, doi:10.1088/0004-637X/804/2/146, S2CID 33401607.
  8. ^ "n Cen". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2021-10-01.
  9. ^ de Vaucouleurs, A. (1957), "Spectral types and luminosities of B, A and F southern stars", Monthly Notices of the Royal Astronomical Society, 117 (4): 449, Bibcode:1957MNRAS.117..449D, doi:10.1093/mnras/117.4.449
  10. ^ Eggen, O. J. (1962), "Space-velocity vectors for 3483 stars with proper motion and radial velocity", Royal Observatory Bulletin, 51: 79, Bibcode:1962RGOB...51...79E.
Allikas: https://en.wikipedia.org/wiki/HD_111968
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