8 Draconis

{{Short description|White-hued chemically unusual star in the constellation Draco}} {{Starbox begin}} {{Starbox image | image = {{Location mark |image=Draco constellation map.svg|alt=|float=center|width=280 |label=|position=right |mark=Red circle.svg|mark_width=10|mark_link=8 Draconis |x=932|y=495 }} | caption = Location of 8 Draconis (circled in red) }} {{Starbox observe | epoch = [[J2000.0]] | equinox = [[J2000.0]] ([[International Celestial Reference System|ICRS]]) | constell = [[Draco (constellation)|Draco]] | ra = {{RA|12|55|28.54856}}<ref name=GaiaDR3/> | dec = {{DEC|+65|26|18.5071}}<ref name=GaiaDR3/> | appmag_v = 5.225<ref name=tycho2/> }} {{Starbox character | type = [[main sequence]]<ref name=GaiaDR3/> | class = F1VmA7(n)<ref name=gray/> | b-v = {{Val|0.303|0.005}}<ref name=Anderson2012/> | u-b = | r-i = | variable = [[Gamma Doradus variable|Gamma Doradus]]<ref name=gcvs/> }} {{Starbox astrometry | radial_v = {{Val|+9.0}}<ref name=rv/> | prop_mo_ra = −3.658<ref name=GaiaDR3/> | prop_mo_dec = −30.126<ref name=GaiaDR3/> | parallax = 33.9667 | p_error = 0.0792 | parallax_footnote = <ref name=GaiaDR3/> | absmag_v = 2.90<ref name=Anderson2012/> }} {{Starbox detail | source = | mass = 1.56<ref name=Plavchan2009/> | radius = 1.50<ref name=Plavchan2009/> | luminosity = 5.75<ref name=Anderson2012/> | temperature = 7,129<ref name=gray/> | gravity = 4.01<ref name=gray/> | metal_fe = −0.14<ref name=gray/> | rotational_velocity = 119.6<ref name=Schröder2009/> | age_myr = {{Val|250|200}}<ref name=Plavchan2009/> }} {{Starbox catalog | names = {{odlist | name=Taiyi | V=IR Draconis | F=8 Dra | BD=+66°778 | FK5=486 | HD=112429 | HIP=63076 | HR=4916 | SAO=15941 }}<ref name=SIMBAD/> }} {{Starbox reference | Simbad = 8+Dra }} {{Starbox end}}

'''8 Draconis''', formally named '''Taiyi''' {{IPAc-en|,|t|ai|'|j|iː}},<ref name=skylive/> is a single<ref name=Eggleton2008/> [[star]] in the northern [[circumpolar constellation]] of [[Draco (constellation)|Draco]]. Based upon an annual [[parallax]] shift of {{val|33.97|ul=mas}} as seen from the [[Earth]],<ref name=hipparcos/> the star is located 96 [[light-year]]s from the [[Sun]]. It is moving further away with a heliocentric [[radial velocity]] of +9 km/s,<ref name=rv/> having come within {{Convert|12.46|pc|ly|disp=out}} some 2.6 million years ago.<ref name=Anderson2012/>

[[File:IRDraLightCurve.png|thumb|left|250px|A [[light curve]] for IR Draconis, adapted from Aerts ''et al.'' (1998)<ref name="Aerts"/>]]

This is an [[F-type main-sequence star]] with a [[stellar classification]] of F1VmA7(n).<ref name=gray/> It is a [[Gamma Doradus variable]] star with a brightness variation of about one tenth of a [[visual magnitude|magnitude]].<ref name=gcvs/> 8 Dra has a relatively high rate of rotation, showing a [[projected rotational velocity]] of 120 km/s.<ref name=Schröder2009/> The star has 1.56 times the [[mass of the Sun]] and 1.50 times the [[Sun's radius]].<ref name=Plavchan2009/> It is radiating 5.75<ref name=Anderson2012/> times the [[Sun's luminosity]] from its [[photosphere]] at an [[effective temperature]] of 7,129 K.<ref name=gray/> An [[infrared excess]] has been detected at [[wavelength]]s of 24 and 70μm, which suggests the presence of a [[circumstellar disk]] orbiting the star.<ref name=Plavchan2009/>

== Nomenclature == 8 Draconis is the star's [[Flamsteed designation]]. It also received the [[variable star designation]] IR Draconis in 2000, after its variability had been discovered using [[Hipparcos]] photometry.<ref name=gcvs/>

The star bore the [[Chinese star names|traditional Chinese name]] of ''Taiyi'',<ref name="Bonnet-Bidaud2009"/><ref name="TriRpt18">{{cite web | url=https://exopla.net/wp-content/uploads/2025/04/2018_WGSN-triennial-report-2015-2018.pdf | page=7 | title=WG Triennial Report (2015-2018) - Star Names |access-date=2018-07-14}}</ref> from 太乙 (''Tài Yǐ'') or 太一 (''Tài Yī'', the Great One), both of which refer to [[Tao]]. Alternatively, Taiyi may refer to [[HD 119476]]{{refn|[[Stellarium (software)|Stellarium]], citing Yi Shitong, 1981<ref name=Yi1981/>}} or [[4 Draconis]],<ref name="Yang2024"/> with [[7 Draconis|7]] and 8 Draconis forming ''Neichu'', representing a private kitchen.<ref name="Ridpath"/> In 2016, the [[International Astronomical Union]] organized a [[IAU Working Group on Star Names|Working Group on Star Names]] (WGSN)<ref name=WGSN/> to catalogue and standardize proper names for stars. The WGSN approved the name ''Taiyi'' for this star on 30 June 2017 and it is now so entered in the IAU Catalog of Star Names.<ref name="IAU-CSN-new"/>

==References== <references> <ref name="Aerts">{{cite journal |last1=Aerts |first1=C. |last2=Eyer |first2=L. |last3=Kestens |first3=E. |title=The discovery of new γ Doradus stars from the HIPPARCOS mission |journal=Astronomy and Astrophysics |date=September 1998 |volume=337 |pages=790–796 |bibcode=1998A&A...337..790A }}</ref>

<ref name=SIMBAD>{{cite simbad | title=8 Dra | access-date=2019-01-23 }}</ref>

<ref name=Eggleton2008>{{citation | title=A catalogue of multiplicity among bright stellar systems | last1=Eggleton | first1=P. P. | last2=Tokovinin | first2=A. A. | journal=Monthly Notices of the Royal Astronomical Society | volume=389 | issue=2 | pages=869 | date=2008 | doi=10.1111/j.1365-2966.2008.13596.x | doi-access=free | postscript=. | bibcode=2008MNRAS.389..869E | arxiv=0806.2878 | s2cid=14878976 }}</ref>

<ref name=Schröder2009>{{citation | last1=Schröder | first1=C. | last2=Reiners | first2=Ansgar | last3=Schmitt | first3=Jürgen H. M. M. | title=Ca II HK emission in rapidly rotating stars. Evidence for an onset of the solar-type dynamo | journal=Astronomy and Astrophysics | volume=493 | issue=3 | pages=1099–1107 | date=January 2009 | doi=10.1051/0004-6361:200810377 | bibcode=2009A&A...493.1099S | doi-access=free | url=http://goedoc.uni-goettingen.de/goescholar/bitstream/handle/1/9690/aa10377-08.pdf?sequence=2 }}{{Dead link|date=July 2023 |bot=InternetArchiveBot |fix-attempted=yes }}</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=WGSN>{{Cite web |url=https://iau.org/WG280 |title=International Astronomical Union {{!}} IAU |website=www.iau.org |access-date=2025-04-09}}</ref>

<ref name=Plavchan2009>{{citation | last1=Plavchan | first1=Peter | last2=Werner | first2=M.W. | last3=Chen | first3=C.H. | last4=Stapelfeldt | first4=K.R. | last5=Su | first5=K.Y.L. | last6=Stauffer | first6=J.R. | last7=Song | first7=I. | display-authors=1 | title=New Debris Disks Around Young, Low-Mass Stars Discovered with the Spitzer Space Telescope | journal=The Astrophysical Journal | volume=698 | issue=2 | pages=1068–94 | date=2009 | doi=10.1088/0004-637X/698/2/1068 | postscript=. | bibcode=2009ApJ...698.1068P | arxiv=0904.0819 | s2cid=51417657 }}</ref>

<ref name=hipparcos>{{cite journal|bibcode=2007A&A...474..653V|title=Validation of the new Hipparcos reduction|journal=Astronomy and Astrophysics|volume=474|issue=2|pages=653–664|last1=Van Leeuwen|first1=F|year=2007|doi=10.1051/0004-6361:20078357|arxiv=0708.1752|s2cid=18759600}}</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|display-authors=etal|last1=Samus|first1=N. N.|last2=Durlevich|first2=O. V.|year=2009}}</ref>

<ref name=rv>{{cite journal|bibcode= 1953GCRV..C......0W |title= General catalogue of stellar radial velocities |journal= Washington |last1= Wilson |first1= Ralph Elmer |year= 1953 }}</ref>

<ref name=gray>{{cite journal|bibcode=2003AJ....126.2048G|title=Contributions to the Nearby Stars (NStars) Project: Spectroscopy of Stars Earlier than M0 within 40 Parsecs: The Northern Sample. I|journal=The Astronomical Journal|volume=126|issue=4|pages=2048|last1=Gray|first1=R. O|last2=Corbally|first2=C. J|last3=Garrison|first3=R. F|last4=McFadden|first4=M. T|last5=Robinson|first5=P. E|year=2003|doi=10.1086/378365|arxiv=astro-ph/0308182|s2cid=119417105}}</ref>

<ref name=tycho2>{{cite journal|bibcode=2000A&A...355L..27H|title=The Tycho-2 catalogue of the 2.5 million brightest stars|journal=Astronomy and Astrophysics|volume=355|pages=L27|last1=Høg|first1=E|last2=Fabricius|first2=C|last3=Makarov|first3=V. V|last4=Urban|first4=S|last5=Corbin|first5=T|last6=Wycoff|first6=G|last7=Bastian|first7=U|last8=Schwekendiek|first8=P|last9=Wicenec|first9=A|year=2000}}</ref>

<ref name=skylive>{{cite web |url=https://theskylive.com/sky/stars/taiyi-8-draconis-star |title=The Sky Live |website=theskylive.com |access-date=2025-04-09}}</ref>

<ref name="IAU-CSN-new">{{cite web |title=IAU Catalog of Star Names |url=https://exopla.net/star-names/modern-iau-star-names/ |access-date=10 May 2025}}</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>

<ref name="Bonnet-Bidaud2009">{{cite journal |last1=Bonnet-Bidaud |first1=Jean-Marc |last2=Praderie |first2=Françoise |last3=Whitfield |first3=Susan |date=March 2009 |title=The Dunhuang Chinese sky: A comprehensive study of the oldest known star atlas |journal=[[Journal of Astronomical History and Heritage]] |volume=12 |issue=1 |pages=39–59 |doi= 10.3724/SP.J.1440-2807.2009.01.04|arxiv=0906.3034 |bibcode=2009JAHH...12...39B}}</ref>

<ref name="Yang2024">{{cite journal |last1=Yang |first1=Bo-Shun |last2=Hoffmann |first2=Susanne M. |date=December 2024 |title=Identification of Z Cam's Historical Counterpart: The Quest for an Ancient Nova |journal=[[Research in Astronomy and Astrophysics]] |volume=24 |issue=12 |pages=125004 |doi=10.1088/1674-4527/ad89aa |arxiv=2410.19010 |bibcode=2024RAA....24l5004Y}}</ref>

<ref name=Yi1981>{{cite book|script-title=zh:中西对照恒星图表|lang=zh|trans-title=Atlas Comparing Chinese and Western Star Maps and Catalogues|last=Yi|first=Shitong|date=April 1981|publisher=科学出版社}}</ref> </references>

[[Category:F-type main-sequence stars]] [[Category:Gamma Doradus variables]] [[Category:Circumstellar disks]] [[Category:Draco (constellation)]] [[Category:Flamsteed objects|Draconis, 08]] [[Category:Henry Draper Catalogue objects|112429]] [[Category:Hipparcos objects|063076]] [[Category:Bright Star Catalogue objects|4916]] [[Category:Objects with variable star designations|Draconis, IR]] [[Category:Stars with proper names|Taiyi]]