{{Short description|Star in the constellation Centaurus}} {{about-distinguish|d Centauri|D Centauri}} {{Starbox begin | name = d Centauri }} {{Starbox image | image = {{Location mark |image=Centaurus constellation map.svg|alt=|float=center|width=280 |label=|position=right |mark=Red circle.svg|mark_width=10|mark_link=HD 117440 |x=520|y=380 }} | caption = Location of d Centauri (circled in red) }} {{Starbox observe | epoch = J2000.0 | constell = [[Centaurus]]<ref name=Anderson_Francis_2012/> | ra = {{RA|13|31|02.66}}<ref name="van Leeuwen2007"/> | dec = {{DEC|−39|24|26.3}}<ref name="van Leeuwen2007"/> | appmag_v = 4.64 + 5.03<ref name=Mason_et_al_2014/> }} {{Starbox character | type = | class = {{nowrap|G7III + G9III}}<ref name=Edwards1976/> | b-v = +1.17 | u-b = +1.03 | variable = Suspected }} {{Starbox astrometry | radial_v = {{val|−2.40|0.74}}<ref name=Kharchenko_et_al_2007/> | prop_mo_ra = {{val|−15.67|0.47}}<ref name="van Leeuwen2007"/> | prop_mo_dec = {{val|−10.49|0.31}}<ref name="van Leeuwen2007"/> | parallax = 3.60 | p_error = 0.49 | parallax_footnote = <ref name="van Leeuwen2007"/> | absmag_v = }} {{Starbox orbit | reference = <ref name=Tokovinin2015/> | period = {{val|83.14|1.26}} | axis = {{val|0.161|0.004}} | inclination = {{val|145.2|4.0}} | node = {{val|146.5|8.6}} | periastron = {{val|1956.12|1.91}} [[Besselian year|B]] | eccentricity = {{val|0.521|0.013}} | periarg = {{val|244.4|3.6}} }} {{Starbox detail | source = | mass = {{val|7.5|0.5}}<ref name=Tetzlaff_et_al_2011/> | radius = | luminosity = | temperature = 4,683<ref name=Martínez_et_al_2014/> | gravity = 1.86<ref name=Martínez_et_al_2014/> | metal_fe = −0.36<ref name=Martínez_et_al_2014/> | age_myr = {{val|40.3|7.6}}<ref name=Tetzlaff_et_al_2011/> | rotational_velocity = 4.5<ref name=Martínez_et_al_2014/> }} {{Starbox catalog | names = {{odlist | B=d Cen | HR=5089 | HD=117440 | CD=−38°8592 | HIP=65936 | SAO=204545 | GC=18254 | NSV=6283 | CCDM=J13310-3924 | WDS=J13310-3924 }} }} {{Starbox reference | Simbad = HD+117440 }} {{Starbox end}}

'''HD 117440''', also known by its [[Bayer designation]] '''d Centauri''', is a [[binary star]]<ref name=Eggleton_Tokovinin_2008/> system in the southern [[constellation]] of [[Centaurus]]. It is visible to the naked eye with a combined [[apparent visual magnitude]] of 3.90.<ref name=Anderson_Francis_2012/> The distance to this system is approximately 900&nbsp;[[light year]]s based on [[stellar parallax|parallax]] measurements.<ref name="van Leeuwen2007"/> It is drifting closer to the [[Sun]] with a [[radial velocity]] of −2&nbsp;km/s.<ref name=Kharchenko_et_al_2007/>

A companion star was first reported by [[Thomas Jefferson Jackson See|T. J. J. See]] in 1897 at an [[angular separation]] of {{val|0.2|ul=arcsecond}} from the primary.<ref name=Mason_et_al_2014/> [[Orbital elements]] for the pair were published by [[William Stephen Finsen|W. S. Finsen]] in 1962<ref name=Eggen1965/> then updated in 1964, yielding an [[orbital period]] of 83.1&nbsp;years with a [[semimajor axis]] of {{val|0.161|u=arcsecond}} and an [[orbital eccentricity|eccentricity]] of 0.52.<ref name=Tokovinin2015/> Both components are [[stellar evolution|evolved]] [[G-type star|G-type]] [[giant star]]s 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.<ref name=Eggen1965/>

==References== {{Reflist|refs=

<ref name="van Leeuwen2007">{{cite journal | title=Validation of the new Hipparcos reduction | last=van Leeuwen | first=F. | journal=Astronomy and Astrophysics | volume=474 | issue=2 | pages=653–664 | year=2007 | arxiv=0708.1752 | bibcode=2007A&A...474..653V | doi=10.1051/0004-6361:20078357 | s2cid=18759600 }} [http://webviz.u-strasbg.fr/viz-bin/VizieR-5?-out.add=.&-source=I/311/hip2&recno=65713 Vizier catalog entry ] </ref>

<ref name=Anderson_Francis_2012>{{cite XHIP|65936}}</ref>

<ref name=Eggleton_Tokovinin_2008>{{cite journal | last1=Eggleton | first1=P. P. | last2=Tokovinin | first2=A. A. | title=A catalogue of multiplicity among bright stellar systems | journal=Monthly Notices of the Royal Astronomical Society | volume=389 | issue=2 | pages=869–879 | date=September 2008 | doi=10.1111/j.1365-2966.2008.13596.x | doi-access=free | s2cid=14878976 | bibcode=2008MNRAS.389..869E | arxiv=0806.2878 }}</ref>

<ref name=Tokovinin2015>{{cite journal | title=Speckle Interferometry at SOAR in 2014 | display-authors=1 | last1=Tokovinin | first1=Andrei | last2=Mason | first2=Brian D. | last3=Hartkopf | first3=William I. | last4=Mendez | first4=Rene A. | last5=Horch | first5=Elliott P. | journal=The Astronomical Journal | volume=150 | issue=2 | id=50 | pages=17 | date=August 2015 | doi=10.1088/0004-6256/150/2/50 | arxiv=1506.05718 | bibcode=2015AJ....150...50T }}</ref>

<ref name=Edwards1976>{{cite journal | title=MK classification for visual binary components. | last=Edwards | first=T. W. | journal=Astronomical Journal | volume=81 | pages=245–249 | date=April 1976 | doi=10.1086/111879 | bibcode=1976AJ.....81..245E }}</ref>

<ref name=Mason_et_al_2014>{{cite journal | display-authors=1 | last1=Mason | first1=B. D. | last2=Wycoff | first2=G. L. | last3=Hartkopf | first3=W. I. | last4=Douglass | first4=G. G. | last5=Worley | first5=C. E. | title=The Washington Visual Double Star Catalog | journal=The Astronomical Journal | year=2014 | volume=122 | issue=6 | page=3466 | bibcode=2001AJ....122.3466M | doi=10.1086/323920 | doi-access=free }}</ref>

<ref name=Eggen1965>{{cite journal | title=Masses, luminosities, colors, and space motions of 228 visual binaries | last=Eggen | first=O. J. | journal=Astronomical Journal | volume=70 | page=19 | date=February 1965 | doi=10.1086/109676 | bibcode=1965AJ.....70...19E }}</ref>

<ref name=Kharchenko_et_al_2007>{{Cite journal | title=Astrophysical supplements to the ASCC-2.5: Ia. Radial velocities of ~55000 stars and mean radial velocities of 516 Galactic open clusters and associations | display-authors=1 | last1=Kharchenko | first1=N. V. | last2=Scholz | first2=R.-D. | last3=Piskunov | first3=A. E. | last4=Röser | first4=S. | last5=Schilbach | first5=E. | journal=Astronomische Nachrichten | volume=328 | issue=9 | pages=889–896 | date=November 1, 2007 | doi=10.1002/asna.200710776 | issn=0004-6337 | arxiv=0705.0878 | bibcode=2007AN....328..889K | s2cid=119323941 }}</ref>

<ref name=Martínez_et_al_2014>{{cite journal | title=The non-active stellar chromosphere: Ca II basal flux | display-authors=1 | last1=Pérez Martínez | first1=M. I. | last2=Schröder | first2=K. -P. | last3=Hauschildt | first3=P. | journal=Monthly Notices of the Royal Astronomical Society | volume=445 | issue=1 | pages=270–279 | date=November 2014 | doi=10.1093/mnras/stu1706 | bibcode=2014MNRAS.445..270P | doi-access=free }}</ref>

<ref name=Tetzlaff_et_al_2011>{{cite journal | title=A catalogue of young runaway Hipparcos stars within 3 kpc from the Sun | display-authors=1 | last1=Tetzlaff | first1=N. | last2=Neuhäuser | first2=R. | last3=Hohle | first3=M. M. | journal=[[Monthly Notices of the Royal Astronomical Society]] | volume=410 | issue=1 | pages=190–200 |date=January 2011 | doi=10.1111/j.1365-2966.2010.17434.x | doi-access=free | s2cid=118629873 | bibcode=2011MNRAS.410..190T | arxiv=1007.4883 }}</ref>

}}

{{Stars of Centaurus}}

{{DEFAULTSORT:Hd 117440}} <!-- Properties --> [[Category:G-type giants]] [[Category:Binary stars]] <!-- Other --> [[Category:Centaurus]] [[Category:Bayer objects|Centauri, d]] [[Category:Durchmusterung objects|CD-38 08592]] [[Category:Henry Draper Catalogue objects|117440]] [[Category:Hipparcos objects|065936]] [[Category:Bright Star Catalogue objects|5089]]