HD 117440

This article is about d Centauri. Not to be confused with D Centauri.
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]

  1. ^ a b c d e f Cite error: The named reference van Leeuwen2007 was invoked but never defined (see the help page).
  2. ^ a b Cite error: The named reference Mason_et_al_2014 was invoked but never defined (see the help page).
  3. ^ Cite error: The named reference Edwards1976 was invoked but never defined (see the help page).
  4. ^ a b Cite error: The named reference Kharchenko_et_al_2007 was invoked but never defined (see the help page).
  5. ^ a b Cite error: The named reference Tokovinin2015 was invoked but never defined (see the help page).
  6. ^ a b Cite error: The named reference Tetzlaff_et_al_2011 was invoked but never defined (see the help page).
  7. ^ a b c d Cite error: The named reference Martínez_et_al_2014 was invoked but never defined (see the help page).
  8. ^ Cite error: The named reference Eggleton_Tokovinin_2008 was invoked but never defined (see the help page).
  9. ^ Cite error: The named reference Anderson_Francis_2012 was invoked but never defined (see the help page).
  10. ^ a b Cite error: The named reference Eggen1965 was invoked but never defined (see the help page).