d Centauri
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Centaurus
Right ascension 13h 31m 02.66s[1]
Declination −39° 24′ 26.3″[1]
Apparent magnitude (V) 4.64 + 5.03[2]
Characteristics
Spectral type G7III + G9III[3]
U−B color index +1.03
B−V color index +1.17
Variable type Suspected
Astrometry
Radial velocity (Rv)−2.40±0.74[4] km/s
Proper motion (μ) RA: −15.67±0.47[1] mas/yr
Dec.: −10.49±0.31[1] mas/yr
Parallax (π)3.60 ± 0.49 mas[1]
Distanceapprox. 900 ly
(approx. 280 pc)
Absolute magnitude (MV)−3.4/−3.2
Orbit[5]
Period (P)83.14±1.26 yr
Semi-major axis (a)0.161±0.004″
Eccentricity (e)0.521±0.013
Inclination (i)145.2±4.0°
Longitude of the node (Ω)146.5±8.6°
Periastron epoch (T)1956.12±1.91 B
Argument of periastron (ω)
(secondary)		244.4±3.6°
Details
Mass7.5±0.5[6] M☉
Surface gravity (log g)1.86[7] cgs
Temperature4,683[7] K
Metallicity [Fe/H]−0.36[7] dex
Rotational velocity (v sin i)4.5[7] km/s
Age40.3±7.6[6] Myr
Other designations
d Cen, NSV 6283, CD−38°8592, GC 18254, HD 117440, HIP 65936, HR 5089, SAO 204545, CCDM J13310-3924, WDS J13310-3924
Database references
SIMBADdata

HD 117440, also known by its Bayer designation d Centauri, is a binary star[8] system in the southern constellation of Centaurus. It is visible to the naked eye with a combined apparent visual magnitude of 3.90.[9] The distance to this system is approximately 900 light years based on parallax measurements.[1] It is drifting closer to the Sun with a radial velocity of −2 km/s.[4]

A companion star was first reported by T. J. J. See in 1897 at an angular separation of 0.2″ from the primary.[2] Orbital elements for the pair were published by W. S. Finsen in 1962[10] then updated in 1964, yielding an orbital period of 83.1 years with a semimajor axis of 0.161″ and an eccentricity of 0.52.[5] Both components are evolved G-type giant stars with a yellow, Sun-like hue. The primary, component A, has an apparent magnitude of +4.64, while the secondary, component B, has an apparent magnitude of +5.03.[10]

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 Mason, B. D.; et al. (2014). "The Washington Visual Double Star Catalog". The Astronomical Journal. 122 (6): 3466. Bibcode:2001AJ....122.3466M. doi:10.1086/323920.
  3. ^ Edwards, T. W. (April 1976). "MK classification for visual binary components". Astronomical Journal. 81: 245–249. Bibcode:1976AJ.....81..245E. doi:10.1086/111879.
  4. ^ a b Kharchenko, N. V.; et al. (November 1, 2007). "Astrophysical supplements to the ASCC-2.5: Ia. Radial velocities of ~55000 stars and mean radial velocities of 516 Galactic open clusters and associations". Astronomische Nachrichten. 328 (9): 889–896. arXiv:0705.0878. Bibcode:2007AN....328..889K. doi:10.1002/asna.200710776. ISSN 0004-6337. S2CID 119323941.
  5. ^ a b Tokovinin, Andrei; et al. (August 2015). "Speckle Interferometry at SOAR in 2014". The Astronomical Journal. 150 (2): 17. arXiv:1506.05718. Bibcode:2015AJ....150...50T. doi:10.1088/0004-6256/150/2/50. 50.
  6. ^ a b Tetzlaff, N.; et al. (January 2011). "A catalogue of young runaway Hipparcos stars within 3 kpc from the Sun". Monthly Notices of the Royal Astronomical Society. 410 (1): 190–200. arXiv:1007.4883. Bibcode:2011MNRAS.410..190T. doi:10.1111/j.1365-2966.2010.17434.x. S2CID 118629873.
  7. ^ a b c d Pérez Martínez, M. I.; et al. (November 2014). "The non-active stellar chromosphere: Ca II basal flux". Monthly Notices of the Royal Astronomical Society. 445 (1): 270–279. Bibcode:2014MNRAS.445..270P. doi:10.1093/mnras/stu1706.
  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. ^ 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.
  10. ^ a b Eggen, O. J. (February 1965). "Masses, luminosities, colors, and space motions of 228 visual binaries". Astronomical Journal. 70: 19. Bibcode:1965AJ.....70...19E. doi:10.1086/109676.
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