{{Short description|Star in the constellation of Draco}} {{Starbox begin | name=χ Draconis }} {{Starbox image | image= {{Location mark |image=Draco constellation map.svg|alt=|float=center|width=260 |label=|position=right |mark=Red circle.svg|mark_width=10|mark_link=χ Draconis |x=320|y=498 }} |caption=Location of χ Draconis (circled) }} {{Starbox observe | epoch=J2000 | ra={{RA|18|21|03.38255}}<ref name=aaa474_2_653/> | dec={{DEC|+72|43|58.2518}}<ref name=aaa474_2_653/> | appmag_v=3.570<ref name=aaa418_989/> | constell=[[Draco (constellation)|Draco]] }} {{Starbox character | class=F7V / K0V<ref name=aar18_1_67/> | b-v=+0.49<ref name=bsc/> | u-b=−0.06<ref name=bsc/> | variable=Suspected<ref name=gcvs/> }} {{Starbox astrometry | radial_v=+32.4<ref name=aaa418_989/> | prop_mo_ra=+531.21<ref name=aaa474_2_653/> | prop_mo_dec=−349.71<ref name=aaa474_2_653/> | parallax=120.05 | p_error=0.15 | parallax_footnote=<ref name=aar18_1_67/> | absmag_v=4.04<ref name=aaa418_989/> }} {{Starbox orbit | reference=<ref name=aj139_6_2308/> | primary=χ Dra Aa | name=χ Dra Ab | period={{val|fmt=commas|0.7680599|0.000061}} | axis={{val|0.1244|0.0011}} | eccentricity={{val|0.428|0.012}} | inclination={{val|74.42|0.58}} | node={{val|230.30|0.51}} | periarg={{val|119.3|1.1}} | periastron={{val|fmt=commas|1984.8324|0.0026}} }} {{Starbox detail | component1=χ Dra Aa | mass={{val|1.029|0.026}}<ref name=aar18_1_67/> | radius={{val|1.20|0.09}}<ref name=aar18_1_67/> | luminosity=1.86<ref name=aar18_1_67/> | temperature={{val|fmt=commas|6,150|150}}<ref name=aar18_1_67/> | metal_fe=−0.41<ref name=aaa418_989/> | rotational_velocity=11<ref name=aaa396_1_131/> | age_gyr=5.3<ref name=aaa418_989/> | component2=χ Dra Ab | mass2={{val|0.748|0.017}}<ref name=aar18_1_67/> | radius2={{val|0.73|0.11}}<ref name=aar18_1_67/> | temperature2={{val|fmt=commas|4,940|200}}<ref name=aar18_1_67/> | luminosity2=0.29<ref name=aar18_1_67/> }} {{Starbox catalog | names={{odlist | B=χ Dra | F=44 Dra | BD=+72°839 | FK5=695 | GJ=713 | HD=170153 | HIP=89937 | HR=6927 | LHS=3379 | LTT=15438 | NSV=10749 | SAO=9087}}<ref name=SIMBAD/> }} {{Starbox reference |Simbad=chi+Dra }} {{Starbox end}} '''Chi Draconis''' is a [[apparent magnitude|magnitude]] 3.6 [[binary star]] in the [[constellation]] [[Draco (constellation)|Draco]]. At a distance of 27 [[light-year]]s, it is one of the 200 or so [[List of nearest bright stars|closest stars]].<ref name="Reylé2021"/>
==Nomenclature== Chi Draconis ([[Romanization of Greek|Latinized]] from χ Draconis, abbreviated χ Dra, Chi Dra) is the star's [[Bayer designation]]. It also has the [[Flamsteed designation]] ''44 Draconis''.
In a 1971 NASA memorandum, this star was listed with the name ''Alahakan''.<ref name=rhoads1971/> According to R. H. Allen's ''[[Star Names]]'', ''Al ʽAuhaḳān'', meaning "the two black bulls, or ravens", was an Arabic name for χ and [[Psi Draconis|ψ Draconis]], among other stars in Draco.<ref name=allen1899/>
In [[Chinese astronomy]], this star is identified as ''Yùnǚsì'' ({{lang|zh|御女四}}), the fourth star of the asterism ''Yùnǚ'' ({{lang|zh|御女}}, Maids-in-waiting; also [[31 Leonis]]).<ref name=AEEA/> Alternatively, it may be ''Zhùshǐ'' ({{lang|zh|柱史}}, Official of Royal Archives),<ref name=Ridpath/> usually identified as [[Phi Draconis|φ Draconis]].<ref name=AEEA/> R. H. Allen (using a now outdated [[romanization of Chinese]]) said it was ''Kwei She''.<ref name=allen1899/>
==Binary system== [[File:Chi Draconis.jpg|thumb|left|χ Draconis in optical light]] χ Draconis is a [[spectroscopic binary]] which has been resolved using [[speckle interferometry]].<ref name=bsc/> The primary is an F7 [[main sequence]] star. The spectral type of the companion cannot be determined directly with any accuracy, but is known to be between G8 and K2 and is assumed to be K0. The properties of the secondary suggest that it is also a main-sequence star. The separation of the two stars varies between about {{val|0.05|ul="}} and {{val|0.2|u="}} during the [[orbital eccentricity|eccentric]] 182-day orbit.<ref name=tomkin1987/>
The primary star has a mass fractionally higher than [[solar mass|the Sun's]], but is significantly larger and hotter resulting in it being 86% more luminous.<ref name=aar18_1_67/> Its age is estimated to be about five billion years.<ref name=aaa418_989/>
The secondary only has about three-quarters the mass of the Sun and is both cooler and smaller. It is only about 29% as luminous.<ref name=aar18_1_67/> It is calculated to be 2.13 magnitudes fainter than the primary, so it would be of sixth magnitude if visible alone.<ref name="apjs227_1_4" />
==Visual companions== Multiple star catalogues list faint widely separated visible companion stars: a 12th-magnitude star and a 14th-magnitude star about {{val|3|ul='}} from χ Draconis, but only about {{val|10|u="}} from each-other.<ref name=wds/> Both have much smaller parallaxes than χ Draconis and are unrelated background objects.<ref name=dr3/>
==See also== * [[List of star systems within 25–30 light-years]] * [[List of nearest stars by spectral type#List of nearest K-type stars|List of nearest K-type stars]]
==References== {{reflist|30em|refs=
<ref name=dr3>{{cite Gaia DR3}}</ref>
<ref name=wds>{{cite journal |last1=Mason |first1=Brian D. |last2=Wycoff |first2=Gary L. |last3=Hartkopf |first3=William I. |last4=Douglass |first4=Geoffrey G. |last5=Worley |first5=Charles E. |title=The 2001 US Naval Observatory Double Star CD-ROM. I. The Washington Double Star Catalog |journal=The Astronomical Journal |date=December 2001 |volume=122 |issue=6 |pages=3466–3471 |doi=10.1086/323920 |issn=0004-6256 |bibcode=2001AJ....122.3466M |doi-access=free}}</ref>
<ref name=tomkin1987>{{cite journal |bibcode=1987AJ.....93.1236T |title=The Orbit of the Speckle and Double-Lined Spectroscopic Binary Chi Draconis |last1=Tomkin |first1=Jocelyn |last2=McAlister |first2=Harold A. |last3=Hartkopf |first3=William I. |last4=Fekel |first4=Francis C. |journal=The Astronomical Journal |date=1987 |volume=93 |page=1236 |doi=10.1086/114404 |doi-access=free }}</ref>
<ref name=gcvs>{{cite journal|bibcode=2009yCat....102025S|title=VizieR Online Data Catalog: General Catalogue of Variable Stars (Samus+ 2007-2013)|journal=VizieR On-line Data Catalog: B/GCVS. Originally Published in: 2009yCat....102025S|volume=1|pages=B/GCVS|display-authors=etal|last1=Samus|first1=N. N.|last2=Durlevich|first2=O. V.|year=2009}}</ref>
<ref name=bsc>{{cite journal|bibcode=1991bsc..book.....H|title=The Bright star catalogue|journal=New Haven|last1=Hoffleit|first1=Dorrit|last2=Jaschek|first2=Carlos|year=1991}}</ref>
<ref name=aaa474_2_653>{{cite journal | last1=van Leeuwen | first1=F. | title=Validation of the new Hipparcos reduction | journal=Astronomy and Astrophysics | volume=474 | issue=2 |date=November 2007 | pages=653–664 | doi=10.1051/0004-6361:20078357 | bibcode=2007A&A...474..653V | arxiv=0708.1752 | s2cid=18759600 }}</ref>
<ref name=SIMBAD>{{cite web | title=chi Dra -- Star in double system | work=SIMBAD | publisher=[[Centre de Données astronomiques de Strasbourg]] | url=http://simbad.u-strasbg.fr/simbad/sim-id?Ident=chi+Dra | accessdate=2011-10-15 }}</ref>
<ref name=aaa418_989>{{cite journal | title=The Geneva-Copenhagen survey of the Solar neighbourhood. Ages, metallicities, and kinematic properties of ˜14 000 F and G dwarfs | display-authors=1 | last1=Nordström | first1=B. | last2=Mayor | first2=M. | last3=Andersen | first3=J. | last4=Holmberg | first4=J. | last5=Pont | first5=F. | last6=Jørgensen | first6=B. R. | last7=Olsen | first7=E. H. | last8=Udry | first8=S. | last9=Mowlavi | first9=N. | journal=Astronomy and Astrophysics | volume=418 | pages=989–1019 |date=May 2004 | doi=10.1051/0004-6361:20035959 | bibcode=2004A&A...418..989N |arxiv = astro-ph/0405198 | s2cid=11027621 }}</ref>
<ref name=aaa396_1_131>{{Cite journal |first1=D. N. |last1=Monin |first2=S. N. |last2=Fabrika |first3=G. G. |last3=Valyavin |year=2002 |title=Magnetic survey of bright northern main sequence stars |journal=Astronomy & Astrophysics |volume=396 |issue=1 |pages=131–141 |doi=10.1051/0004-6361:20021425 |bibcode=2002A&A...396..131M|doi-access=free }}</ref>
<ref name=aj139_6_2308>{{cite journal | display-authors=1 | last1=Farrington | first1=C. D. | last2=ten Brummelaar | first2=T. A. | last3=Mason | first3=B. D. | last4=Hartkopf | first4=W. I. | last5=Alister | first5=H. A. | last6=Raghavan | first6=D. | last7=Turner | first7=N. H. | last8=Sturmann | first8=L. | last9=Sturmann | first9=J. | title=Separated Fringe Packet Observations with the CHARA Array. I. Methods and New Orbits for χ Draconis, HD 184467, and HD 198084 | journal=The Astronomical Journal | volume=139 | issue=6 | pages=2308–2318 |date=June 2010 | doi=10.1088/0004-6256/139/6/2308 | bibcode=2010AJ....139.2308F | doi-access=free }}</ref>
<ref name=aar18_1_67>{{cite journal | last1=Torres | first1=G. | last2=Andersen | first2=J. | last3=Giménez | first3=A. | title=Accurate masses and radii of normal stars: modern results and applications | journal=The Astronomy and Astrophysics Review | year=2010 | volume=18 | issue=1–2 | pages=67–126 | doi=10.1007/s00159-009-0025-1 | bibcode=2010A&ARv..18...67T |arxiv = 0908.2624 | s2cid=14006009 }} See p. 56, entry #15.</ref>
<ref name=apjs227_1_4>{{cite journal |last1=Hutter |first1=D. J. |last2=Zavala |first2=R. T. |last3=Tycner |first3=C. |last4=Benson |first4=J. A. |last5=Hummel |first5=C. A. |last6=Sanborn |first6=J. |last7=Franz |first7=O. G. |last8=Johnston |first8=K. J. |title=Surveying the Bright Stars by Optical Interferometry. I. A Search for Multiplicity Among Stars of Spectral Types F-K |journal=The Astrophysical Journal Supplement Series |date=9 November 2016 |volume=227 |issue=1 |pages=4 |doi=10.3847/0067-0049/227/1/4|arxiv=1609.05254 |bibcode=2016ApJS..227....4H |s2cid=118803592 |doi-access=free }}</ref>
<ref name="Reylé2021">{{cite journal |first1=Céline |last1=Reylé |first2=Kevin |last2=Jardine |first3=Pascal |last3=Fouqué |first4=Jose A. |last4=Caballero |first5=Richard L. |last5=Smart |first6=Alessandro |last6=Sozzetti |date=30 April 2021 |title=The 10 parsec sample in the Gaia era |journal=[[Astronomy & Astrophysics]] |volume=650 |issue= |pages=A201 |doi=10.1051/0004-6361/202140985 |arxiv=2104.14972 |bibcode=2021A&A...650A.201R |s2cid=233476431}} Data available at https://gruze.org/10pc/ {{Webarchive|url=https://web.archive.org/web/20230312171927/http://gruze.org/10pc/ |date=12 March 2023 }}</ref>
<ref name=allen1899>{{citation | first1=R. H. | last1=Allen | title=Star Names: Their Lore and Meaning | date=1899 | url=https://penelope.uchicago.edu/Thayer/E/Gazetteer/Topics/astronomy/_Texts/secondary/ALLSTA/Draco*.html | page=210 }}</ref>
<ref name=rhoads1971>{{citation | first=Jack W. | last=Rhoads | title=Technical Memorandum 33-507-A Reduced Star Catalog Containing 537 Named Stars | publisher=Jet Propulsion Laboratory, California Institute of Technology | url=https://ntrs.nasa.gov/api/citations/19720005197/downloads/19720005197.pdf | date=November 15, 1971 | postscript=. }}</ref>
<ref name=AEEA>{{cite web |title=AEEA 天文教育資訊網 |trans-title=Activities of Exhibition and Education in Astronomy |language=zh |url=http://aeea.nmns.edu.tw/2006/0606/ap060610.html |archive-url=https://web.archive.org/web/20110521234349/http://aeea.nmns.edu.tw/2006/0606/ap060610.html |archive-date=21 May 2011 |url-status=dead}}</ref>
<ref name=Ridpath>{{cite web |last=Ridpath |first=Ian |author-link=Ian Ridpath |title=Star Tales - Draco |url=http://ianridpath.com/startales/draco.html |access-date=10 May 2025}}</ref>
}}
==External links== * [https://web.archive.org/web/20051024072413/http://www.ari.uni-heidelberg.de/aricns/cnspages/4c01485.htm ARICNS] * [https://web.archive.org/web/20000824113925/http://www.solstation.com/stars/chidrac2.htm Chi Draconis 2] at SolStation. * [https://web.archive.org/web/20050928213551/http://nstars.arc.nasa.gov/searches/starinfo.cfm?partb=1821p7243&starpage=0 nStars database entry]
{{Stars of Draco}}
[[Category:Draco (constellation)]] [[Category:Binary stars]] [[Category:Bayer objects|Draconis, Chi]] [[Category:F-type main-sequence stars]] [[Category:K-type main-sequence stars]] [[Category:Hipparcos objects|089937]] [[Category:Flamsteed objects|Draconis, 44]] [[Category:Bright Star Catalogue objects|6927]] [[Category:Henry Draper Catalogue objects|170153]] [[Category:Durchmusterung objects|BD+72 0839]] [[Category:Gliese and GJ objects|0713]]