{{short description|Star in the constellation Draco}} {{Starbox begin}} {{Starbox image | image = {{Location mark | image=Draco IAU.svg | float=center | width=240 | position=right | mark=Red circle.svg | mark_width=10 | mark_link=ι Exa | x%=68.9 | y%=29.9 }} | caption=Location of κ Draconis (circled) near the center }} {{Starbox observe | epoch = J2000 | ra = {{RA|12|33|28.94206}}<ref name=GaiaDR2/> | dec = {{DEC|+69|47|17.6331}}<ref name=GaiaDR2/> | appmag_v = 3.82<ref name=aj76_1058/> | constell = [[Draco (constellation)|Draco]] }} {{Starbox character | type = | class = B6 IIIe<ref name=mnras309_1_221/> | b-v = −0.11<ref name=aj76_1058/> | u-b = −0.61<ref name=aj76_1058/> | r-i = | variable = }} {{Starbox astrometry | radial_v = −11.4<ref name=gcsrv/> | prop_mo_ra = −58.162<ref name=GaiaDR2/> | prop_mo_dec = +11.802<ref name=GaiaDR2/> | parallax = 7.1387 | p_error = 0.3291 | parallax_footnote = <ref name=GaiaDR2/> | absmag_v = −1.95 + 2.4<ref name=Klement/> }} {{Starbox orbit | reference = <ref name=Klement/> | period_unitless = {{val|61.5496|0.0058}} d | eccentricity = 0 | k1 = {{val|6.90|0.15}} | inclination = {{val|130.0|3.4}} | node = {{val|118.0|1.3}} | axis_unitless = {{val|0.487|0.021|ul=au}} }} {{Starbox detail | component1 = κ Dra A | mass = {{val|3.65|0.48}}<ref name=Klement/> | temperature = {{val|fmt=commas|13982|392}}<ref name=Klement/> | radius = {{val|5.85|0.18}}<ref name=Klement/> | luminosity = {{val|fmt=commas|1178|151}}<ref name=Klement/> | metal_fe = −0.65<ref name=Anderson2012/> | gravity = 3.5<ref name=Saad2004/> | rotational_velocity = {{val|200|12}}<ref name=Klement/> | age_gyr = | component2 = κ Dra B | mass2 = {{val|0.426|0.043}}<ref name=Klement/> | temperature2 = {{val|fmt=commas|16700|2000}}<ref name=Klement/> | radius2 = {{val|0.69|0.07}}<ref name=Klement/> | luminosity2 = {{val|33|17}}<ref name=Klement/> | rotational_velocity2 = {{val|35|10}}<ref name=Klement/> }} {{Starbox catalog | names = {{odlist | B=κ Dra | F=5 Dra | BD=+70°703 | FK5=472 | HD=109387 | HIP=61281 | HR=4787 | SAO=7593 }}<ref name=SIMBAD/> }} {{Starbox reference | Simbad = kap+Dra }} {{Starbox end}}
'''Kappa Draconis''', [[Latinisation of names|Latinized]] from κ Draconis, is a [[blue giant]] [[star]] located in the northern [[circumpolar constellation]] of [[Draco (constellation)|Draco]]. At an [[apparent magnitude]] of 3.88, it is barely visible to the [[naked eye]] when artificial lighting from cities is present. Nevertheless, it is a powerful star, approximately five time as massive as the [[Sun]]. It is about 460 [[light-year]]s away, and is 1,400 times brighter than the Sun.
The star is currently located at [[declination]] {{DEC|+69|47|18}} ([[right ascension]] {{RA|12|33|29.0}}), but due to the effects of [[precession]], Kappa Draconis was the nearest star to the [[north celestial pole]] visible to the naked eye from 1793 BC to approximately 1000 BC, though it was 6° removed from perfect alignment, making it only an approximate [[pole star]], similar to the roughly 7° variance from perfect alignment of the much brighter (magnitude 2.08) star [[Beta Ursae Minoris|Kochab]], at the same time during Earth's precession.{{citation needed|date=February 2017}}
==Properties== [[File:KappaDraLightCurve.png|thumb|left|A [[light curve]] for Kappa Draconis, plotted from ''[[Transiting Exoplanet Survey Satellite|TESS]]'' data<ref name=MAST/>]] Kappa Draconis is a classical [[Be star]], displaying [[Balmer line|Balmer emission lines]] in its [[stellar spectrum|spectrum]].<ref name=Banerjee2012/> It is spinning rapidly with a [[projected rotational velocity]] of 170 km/s.<ref name=Saad2004/> The star is thought to be just entering its [[red giant]] phase, having exhausted the supply of [[hydrogen]] in its [[stellar core|core]]. Over the next several thousand years, the star will expand, becoming more powerful but with a much cooler surface temperature. Tens of thousands of years from now, Kappa Draconis will appear much brighter, probably shining with a reddish hue.{{citation needed|date=February 2017}}
Kappa Draconis is a single-lined [[spectroscopic binary]].<ref name=Hutter/> The main Be star is orbited by another stellar companion, on a circular orbit with a period of 61.555 days.<ref name=Saad2005/> The secondary is an unusual star, a [[subdwarf B star]].<ref name=Klement/>
The [[General Catalogue of Variable Stars]] lists Kappa Draconis as a Gamma Cassiopeiae type star, a type of eruptive [[irregular variable]] star, whose visual magnitude varies from 3.82 to 4.01.<ref name="gcvs"/> However Balona and Dziembowsk classify it as a Zeta Ophiuchi star, a type of [[Variable_star#Pulsating_variable|pulsating variable]] star, with a primary period of 10.4 hours.<ref name="Balona"/>
==Chinese name== [[File:Kappa Draconis.jpg|left|thumb|κ Draconis in optical light]] In [[Chinese astronomy|Chinese]], {{lang|zh|紫微右垣}} ({{lang|zh-Latn|Zǐ Wēi Yòu Yuán}}), meaning ''[[Purple Forbidden enclosure|Right Wall of Purple Forbidden Enclosure]]'', refers to an asterism consisting of κ Draconis, [[Alpha Draconis|α Draconis]], [[Lambda Draconis|λ Draconis]], [[24 Ursae Majoris]], [[43 Camelopardalis]], [[Alpha Camelopardalis|α Camelopardalis]] and [[BK Camelopardalis]].<ref name=zh/> Consequently, the [[Chinese star name|Chinese name]] for κ Draconis itself is {{lang|zh|紫微右垣二}} ({{lang|zh-Latn|Zǐ Wēi Yòu Yuán èr}}, {{langx|en|the Second Star of Right Wall of Purple Forbidden Enclosure}}.),<ref name=aeea/> representing {{lang|zh|少尉}} ({{lang|zh-Latn|Shǎowèi}}), meaning ''Second Chief Judge''<ref name=lcsd/> {{clear left}} ==References== <references> <ref name=lcsd>[http://www.lcsd.gov.hk/CE/Museum/Space/Research/StarName/e_research_chinengstarzone_b.htm#PrupleForbiddenEnclosure English-Chinese Glossary of Chinese Star Regions, Asterisms and Star Name] {{webarchive|url=https://web.archive.org/web/20080924022136/http://www.lcsd.gov.hk/CE/Museum/Space/Research/StarName/e_research_chinengstarzone_b.htm |date=2008-09-24 }}, Hong Kong Space Museum. Accessed on line November 23, 2010.</ref>
<ref name=aeea>{{in lang|zh}} [http://aeea.nmns.edu.tw/2006/0606/ap060611.html AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 6 月 11 日] {{Webarchive|url=https://web.archive.org/web/20110522121054/http://aeea.nmns.edu.tw/2006/0606/ap060611.html |date=2011-05-22 }}</ref>
<ref name=zh>{{in lang|zh}} ''中國星座神話'', written by 陳久金. Published by 台灣書房出版有限公司, 2005, {{ISBN|978-986-7332-25-7}}.</ref>
<ref name=GaiaDR2>{{Cite Gaia DR2|1683102889080253312}}</ref>
<ref name=Saad2005>{{cite journal | doi=10.1007/s10509-005-4438-7 | title=Spectrum Disentangling and Orbital Solution for κ Dra | year=2005 | last1=Saad | first1=S. M. | last2=Kubát | first2=J. | last3=Hadrava | first3=P. | last4=Harmanec | first4=P. | last5=Koubský | first5=P. | last6=Škoda | first6=P. | last7=Šlechta | first7=M. | last8=Korčáková | first8=D. | last9=Yang | first9=S. | journal=Astrophysics and Space Science | volume=296 | issue=1–4 | pages=173–177 | bibcode=2005Ap&SS.296..173S | s2cid=189844885}}</ref>
<ref name=MAST>{{cite web |title=MAST: Barbara A. Mikulski Archive for Space Telescopes |url=https://mast.stsci.edu/portal/Mashup/Clients/Mast/Portal.html |publisher=Space Telescope Science Institute |access-date=8 December 2021}}</ref>
<ref name="gcvs">{{cite web |title=Query= kap Dra |url=http://www.sai.msu.su/gcvs/cgi-bin/search2.cgi?search=kap+Dra |website=General Catalog of Variable Stars |publisher=Sternberg Astronomical Institute |access-date=19 December 2022}}</ref>
<ref name=Anderson2012>{{citation | title=XHIP: An extended hipparcos compilation | last1=Anderson | first1=E. | last2=Francis | first2=Ch. | journal=Astronomy Letters | volume=38 | issue=5 | pages=331 | year=2012 | bibcode=2012AstL...38..331A | doi=10.1134/S1063773712050015 | arxiv=1108.4971 | s2cid=119257644 | postscript=. }}</ref>
<ref name=Banerjee2012>{{citation | title=Optical spectroscopy of Galactic field classical Be stars | last1=Banerjee | first1=Gourav | last2=Mathew | first2=Blesson | last3=Paul | first3=K. T. | last4=Subramaniam | first4=Annapurni | last5=Bhattacharyya | first5=Suman | last6=Anusha | first6=R. | display-authors=1 | postscript=. | journal=Monthly Notices of the Royal Astronomical Society | volume=500 | issue=3 | pages=3926–3943 | date=January 2021 | doi=10.1093/mnras/staa3469 | doi-access=free | arxiv=2011.08622 | bibcode=2021MNRAS.500.3926B }}</ref>
<ref name="Balona">{{cite journal |last1=Balona |first1=L. A. |last2=Dziembowski |first2=W. A. |title=Excitation and visibility of high-degree modes in stars |journal=Monthly Notices of the Royal Astronomical Society |date=October 1999 |volume=309 |issue=1 |pages=221–232 |doi=10.1046/j.1365-8711.1999.02821.x |bibcode=1999MNRAS.309..221B |doi-access=free }}</ref>
<ref name=gcsrv>{{cite journal | last=Wilson | first=R. E. | date=1953 | title=General Catalogue of Stellar Radial Velocities | journal=Carnegie Institute Washington D.C. Publication | publisher=[[Carnegie Institute of Washington D.C.]] | bibcode=1953GCRV..C......0W }}</ref>
<ref name=aj76_1058>{{citation | last1=Crawford | first1=D. L. | last2=Barnes | first2=J. V. | last3=Golson | first3=J. C. | title=Four-color, H-beta, and UBV photometry for bright B-type stars in the northern hemisphere | journal=The Astronomical Journal | date=1971 | pages=1058 | volume=76 | bibcode=1971AJ.....76.1058C | doi=10.1086/111220 }}</ref>
<ref name=mnras309_1_221>{{citation | last1=Balona | first1=L. A. | last2=Dziembowski | first2=W. A. | title=Excitation and visibility of high-degree modes in stars | journal=[[Monthly Notices of the Royal Astronomical Society]] | volume=309 | issue=1 | pages=221–232 |date=October 1999 | doi=10.1046/j.1365-8711.1999.02821.x | bibcode=1999MNRAS.309..221B | doi-access=free }}</ref>
<ref name=Saad2004>{{cite journal | doi=10.1051/0004-6361:20034241 | title=Properties and nature of Be stars. XXIII. Long-term variations and physical properties of κ Dra | year=2004 | last1=Saad | first1=S. M. | last2=Kubát | first2=J. | last3=Koubský | first3=P. | last4=Harmanec | first4=P. | last5=Škoda | first5=P. | last6=Korčáková | first6=D. | last7=Krtička | first7=J. | last8=Šlechta | first8=M. | last9=Božić | first9=H. | last10=Ak | first10=H. | last11=Hadrava | first11=P. | last12=Votruba | first12=V. | journal=Astronomy & Astrophysics | volume=419 | issue=2 | pages=607–621 | arxiv=astro-ph/0401491 | bibcode=2004A&A...419..607S | s2cid=119007669| doi-access=free }}</ref>
<ref name=Hutter>{{cite journal | title=Surveying the Bright Stars by Optical Interferometry. III. A Magnitude-limited Multiplicity Survey of Classical Be Stars | year=2021 | last1=Hutter | first1=D. J. | last2=Tycner | first2=C. | last3=Zavala | first3=R. T. | last4=Benson | first4=J. A. | last5=Hummel | first5=C. A. | last6=Zirm | first6=H. | journal=The Astrophysical Journal Supplement Series | volume=257 | issue=2 | page=69 | doi=10.3847/1538-4365/ac23cb | arxiv=2109.06839 | bibcode=2021ApJS..257...69H | s2cid=237503492 | doi-access=free }}</ref>
<ref name=SIMBAD>{{cite simbad | title=kap Dra | access-date=2012-02-06 }}</ref>
<ref name=Klement>{{cite journal | arxiv=2210.03090 | bibcode=2022ApJ...940...86K | doi=10.3847/1538-4357/ac98b8 | title=Dynamical Masses of the Primary be Star and Secondary sdB Star in the Single-lined Binary κ Dra (B6 IIIe) | year=2022 | last1=Klement | first1=Robert | last2=Baade | first2=Dietrich | last3=Rivinius | first3=Thomas | last4=Gies | first4=Douglas R. | last5=Wang | first5=Luqian | last6=Labadie-Bartz | first6=Jonathan | last7=Dos Santos | first7=Pedro Ticiani | last8=Monnier | first8=John D. | last9=Carciofi | first9=Alex C. | last10=Mérand | first10=Antoine | last11=Anugu | first11=Narsireddy | last12=Schaefer | first12=Gail H. | last13=Bouquin | first13=Jean-Baptiste Le | last14=Davies | first14=Claire L. | last15=Ennis | first15=Jacob | last16=Gardner | first16=Tyler | last17=Kraus | first17=Stefan | last18=Setterholm | first18=Benjamin R. | last19=Labdon | first19=Aaron | journal=The Astrophysical Journal | volume=940 | issue=1 | page=86 | s2cid=252735283 | doi-access=free }}</ref> </references>
==External links== * [https://web.archive.org/web/20061011012648/http://www.astro.uiuc.edu/%7Ekaler/sow/kappadra.html Kappa Draconis] by Jim Kaler
{{Stars of Draco}}
[[Category:B-type giants]] [[Category:Be stars]] [[Category:Spectroscopic binaries]] [[Category:Draco (constellation)]] [[Category:Bayer objects|Draconis, Kappa]] [[Category:Durchmusterung objects]] [[Category:Flamsteed objects|Draconis, 05]] [[Category:Henry Draper Catalogue objects|109387]] [[Category:Hipparcos objects|061281]] [[Category:Bright Star Catalogue objects|4787]] [[Category:Northern pole stars]] [[Category:B-type subdwarfs]]