| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Centaurus[1] |
| Right ascension | 12h 53m 26.20s[2] |
| Declination | −40° 10′ 43.9″[2] |
| Apparent magnitude (V) | +4.25[1] |
| Characteristics | |
| Spectral type | A7IV[3] or A7V[4] |
| B−V color index | +0.224±0.014[1] |
| Astrometry | |
| Proper motion (μ) | RA: +70.84±0.14[2] mas/yr Dec.: −22.54±0.10[2] mas/yr |
| Parallax (π) | 21.95±0.19 mas[2] |
| Distance | 149 ± 1 ly (45.6 ± 0.4 pc) |
| Absolute magnitude (MV) | +0.86[5] |
| Details | |
| A | |
| Mass | 2.07[6] M☉ |
| Radius | 3.3[6] R☉ |
| Luminosity | 34.34[1] L☉ |
| Surface gravity (log g) | 3.87±0.14[7] cgs |
| Temperature | 7,400[6] K |
| Rotational velocity (v sin i) | 92.4±4.6[5] km/s |
| Age | 900[6] Myr |
| B | |
| Mass | 0.88[6] M☉ |
| Radius | 0.80[6] R☉ |
| Temperature | 5,300[6] K |
| Age | 900[6] Myr |
| Other designations | |
| n Cen, CD−39°7893, FK5 482, GC 17489, GJ 488.1, GJ 9422, HD 111968, HIP 62896, HR 4889, SAO 203907[8] | |
| Database references | |
| SIMBAD | data |
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.[1] The star is located at a distance of approximately 149 light years based on parallax.[2] The radial velocity of the star is poorly constrained, with an estimated value of 2.5 km/s.[1]
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[1] 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 has a projected separation of 26 astronomical units from the primary, giving an estimated orbital period of 80 years. 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
[edit]- ^ a b c d e f g 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.
- ^ 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
- ^ 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.
- ^ 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.
- ^ 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.
- ^ a b c d e f g h i j k l m n 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
- ^ 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.
- ^ "n Cen". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2021-10-01.
- ^ 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
- ^ 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.
