Delta Boötis

{{Short description|Double star in the northern constellation Boötes}} {{Starbox begin | name = δ Boötis }} {{Starbox image | image = {{Location mark | image=Boötes IAU.svg | float=center | width=240 | position=right | mark=Red circle.svg | mark_width=10 | mark_link=δ Boo | x%=33.2 | y%=41.6 }} | caption=Location of δ Boötis (circled) }} {{Starbox observe 2s | epoch = J2000 | constell = [[Boötes]]<ref name=xhip/> | component1 = A | ra1 = {{RA|15|15|30.16282}}<ref name="DR3" /> | dec1 = {{DEC|+33|18|53.3925}}<ref name="DR3" /> | appmag_v1 = 3.482<ref name="mnras172_667" /> | component2 = B | ra2 = {{RA|15|15|38.34898}}<ref name="GaiaDR2" /> | dec2 = {{DEC|+33|19|15.3187}}<ref name="GaiaDR2" /> | appmag_v2 = 7.81<ref name="aj139_1105" /> }} {{Starbox character | component1 = A | type = | class = G8 III<ref name="al34_1_17" /> | b-v = +0.951<ref name="mnras172_667" /> | u-b = +0.656<ref name="mnras172_667" /> | variable = | component2 = B | type2 = | class2 = G0 V<ref name="aj139_1105" /> | b-v2 = +0.59<ref name="aj139_1105" /> | u-b2 = +0.02<ref name="aj139_1105" /> | variable2 = }} {{Starbox astrometry | component1 = A | radial_v = {{val|−12.29|0.16}}<ref name="Soubiran_et_al_2008" /> | prop_mo_ra = +84.383 | prop_mo_dec = −111.591 | pm_footnote = <ref name="DR3" /> | parallax = 27.0746 | p_error = 0.1256 | parallax_footnote = <ref name="DR3" /> | absmag_v = +0.700<ref name="BohmVitense2000" /> | component2 = B | radial_v2 = {{val|−11.83|0.18}}<ref name="GaiaDR2" /> | prop_mo_ra2 = +82.918 | prop_mo_dec2 = −110.075 | pm_footnote2 = <ref name=GaiaDR3B /> | parallax2 = 27.1573 | p_error2 = 0.0178 | parallax_footnote2 = <ref name=GaiaDR3B/> | absmag_v2 = +4.96<ref name=xhip/> }} {{Starbox detail | component1 = A | mass = 1.5<ref name="Luck2015" /> | radius = {{val|11.43|0.07}}<ref name="baines" /> | luminosity = {{val|58.1}}<ref name="soubiran" /> | temperature = {{val|4810|30|fmt=commas}}<ref name="soubiran" /> | metal_fe = {{val|−0.35|0.03}}<ref name="soubiran" /> | gravity = {{val|2.38|0.09}}<ref name="soubiran" /> | rotational_velocity = 3.6<ref name="aj135_1_209" /> | age_gyr = | component2 = B | mass2 = 0.98<ref name="Luck2015" /> | radius2 = {{val|0.91|0.02}}<ref name=GaiaDR2 /> | luminosity2 = 0.87<ref name="Luck2015" /> | temperature2 = {{val|5812|67|fmt=commas}}<ref name="Luck2015" /> | age_gyr2 = 3.09<ref name="Luck2015" /> }} {{Starbox catalog | names = {{odlist | name=STF 4027 | ADS=9559 | WDS=15155+3319 }}<ref name="SIMBAD" /> | component1 = A | names1 = {{odlist | name=Qigong | B=δ Boo | F=49 Boötis | BD=+33 2561 | FK5=563 | HD=135722 | HIP=74666 | HR=5681 | SAO=64589 }}<ref name="SIMBAD" /> | component2 = B | names2 = {{odlist | BD=+33 2562 | HIP=74674 | SAO=64591 }}<ref name="SIMBAD_B" /> }} {{Starbox reference | Simbad = HD+135722|sn=A | Simbad2 = del+Boo+B|sn2=B }} {{Starbox end}}

'''Delta Boötis''', [[Romanization of Greek|Latinized]] from δ Boötis formally named '''Qigong''',<ref name=IAU-CSN/> is a [[double star]] in the northern [[constellation]] of [[Boötes]], forming the easternmost member of the constellation's kite-shaped [[Asterism (astronomy)|asterism]] of brighter stars.<ref name="English2014" /> Based upon [[stellar parallax|parallax]] measurements, it is located at a distance of approximately {{Convert|120.5|ly|pc|abbr=off|lk=on}} from the [[Earth]].<ref name="DR3" /> The [[apparent visual magnitude]] of this star is 3.5,<ref name="mnras172_667" /> making it visible to the [[naked eye]] [[Bortle Dark-Sky Scale|even during a Full Moon]]. The magnitude 7.81<ref name="aj139_1105" /> companion can be viewed in binoculars or a small telescope.<ref name="English2014" />

==Nomenclature== ''Delta Boötis'' is a [[Bayer designation]] that is [[Romanization of Greek|Latinized]] from δ Boötis, and abbreviated Delta Boo or δ Boo. This star is sometimes called Princeps {{IPAc-en|'|p|r|I|n|s|E|p|s}}, meaning ''prince'' or ''prime'' in [[Latin]].<ref>{{OED|princeps}}</ref> The origin of this name is unclear, although it usually appears in an [[astrology|astrological]] context.<ref name="robson2005" /><ref name=Princeps/>

In [[Chinese astronomy]], {{lang|zh|七公}} ({{lang|zh-Latn|Qī Gōng}}), meaning ''[[Heavenly Market enclosure|Seven Excellencies]]'', refers to an asterism consisting of δ Boötis, [[42 Herculis]], [[Tau Herculis|τ Herculis]], [[Phi Herculis|φ Herculis]], [[Chi Herculis|χ Herculis]], [[Nu1 Boötis|ν1 Boötis]] and [[Mu1 Boötis|μ1 Boötis]].<ref>{{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> Consequently, the [[Chinese star names|Chinese name]] for δ Boötis itself is {{lang|zh|七公七}} ({{lang|zh-Latn|Qī Gōng qī}}, {{langx|en|the Seventh Star of Seven Excellencies}}).<ref>{{in lang|zh}} [http://aeea.nmns.edu.tw/2006/0606/ap060626.html AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 6 月 26 日] {{Webarchive|url=https://web.archive.org/web/20110522121442/http://aeea.nmns.edu.tw/2006/0606/ap060626.html |date=2011-05-22 }}</ref> R. H. Allen's ''[[Star Names]]'' (1899) referred to this asterism as ''Tseih Kung'', "the Seven Princes".<ref name=allen1899/> The [[IAU Working Group on Star Names]] approved the name Qigong for Delta Boötis A on 15 April 2026, after the Chinese constellation.<ref name=IAU-CSN/>

With [[Beta Boötis|β Boötis]] (Nekkar), [[Gamma Boötis|γ Boötis]] (Seginus), and [[Mu Boötis|μ Boötis]] (Alkalurops), this star formed an asterism called in Arabic ''Al Dhi᾽bah'', the female wolves or hyenas; similar names are found in [[Draco (constellation)|Draco]] (see [[Zeta Draconis|Aldhibah]]).<ref name=allen1899/> Rhoads (1971) listed ''Thiba'' as a name for δ Boötis.<ref name=rhoads1971/>

==Properties== [[Image:Delta Bootis.jpg|thumb|left|δ Boötis in optical light]] This system consists of a pair of stars located in physical proximity to each other and sharing a similar motion through space, suggesting that they may form a [[binary star]] system. Based upon their angular separation and their distance, they have a [[projected separation]] of 3,800 [[Astronomical Unit]]s (AU). If they are gravitationally bound to each other, the [[orbital period]] of the system would be at least 120,000 years.<ref name="kaler" />

The brighter member of the pair has a [[stellar classification]] of G8 III,<ref name="al34_1_17" /> indicating that it has exhausted the supply of hydrogen at its core and [[stellar evolution|evolved]] into a [[giant star]]. It now has a radius more than eleven times the radius of the Sun.<ref name="baines" /> Compared to the [[Sun]], this star appears deficient in elements other than hydrogen and helium—what astronomers term the star's [[metallicity]]. The outer envelope of this star has an [[effective temperature]] of 4,810 K,<ref name="soubiran" /> which is what gives it the characteristic yellow hue of a [[G-type star]].<ref name="csiro" />

The secondary component has a stellar classification of G0 V,<ref name="aj139_1105" /> which suggests it is a [[main sequence]] star that may be similar in physical properties to the Sun. The apparent visual magnitude of this star is 7.81,<ref name="aj139_1105" /> making it much less luminous than the primary component.<ref name="brightness" />

==References== {{reflist|1=30em|refs=

<ref name="SIMBAD">{{cite simbad | title=del Boo | access-date=2021-06-14}}</ref>

<ref name="SIMBAD_B">{{cite simbad | title=BD+33 2562 | access-date=2021-06-14}}</ref>

<ref name="soubiran">{{Citation | title=Gaia FGK benchmark stars: Fundamental Teff and log g of the third version | display-authors=1 | last1=Soubiran | first1=C. | last2=Creevey | first2=O. L. | last3=Lagarde | first3=N. | last4=Brouillet | first4=N. | last5=Jofré | first5=P. | last6=Casamiquela | first6=L. | last7=Heiter | first7=U. | last8=Aguilera-Gómez | first8=C. | last9=Vitali | first9=S. | last10=Worley | first10=C. | last11=de Brito Silva | first11=D. | journal=Astronomy and Astrophysics | volume=682 | pages=A145 | date=February 2024 | doi=10.1051/0004-6361/202347136 | arxiv=2310.11302 | issn=0004-6361 | bibcode=2024A&A...682A.145S }} [https://vizier.cds.unistra.fr/viz-bin/VizieR?-source=J/A%2BA/682/A145&HIP=HIP74666 Delta Boo's database entry] at [[VizieR]].</ref>

<ref name="baines">{{citation | title=Angular Diameters and Fundamental Parameters of Forty-four Stars from the Navy Precision Optical Interferometer | last1=Baines | first1=Ellyn K. | last2=Thomas Armstrong | first2=J. | last3=Clark | first3=James H. | last4=Gorney | first4=Jim | last5=Hutter | first5=Donald J. | last6=Jorgensen | first6=Anders M. | last7=Kyte | first7=Casey | last8=Mozurkewich | first8=David | last9=Nisley | first9=Ishara | last10=Sanborn | first10=Jason | last11=Schmitt | first11=Henrique R. | last12=Van Belle | first12=Gerard T. | display-authors=1 | journal=The Astronomical Journal | date=2021 |volume=162 |issue=5 |page=198 | doi=10.3847/1538-3881/ac2431 | doi-access=free | bibcode=2021AJ....162..198B | arxiv=2211.09030}}</ref>

<ref name="BohmVitense2000">{{citation | title=Ultraviolet Emission Lines in BA and Non-BA Giants | display-authors=1 | last1=Böhm-Vitense | first1=Erika | last2=Carpenter | first2=Kenneth G. | last3=Robinson | first3=Richard D. | journal=The Astrophysical Journal | postscript=. | volume=545 | issue=2 | pages=992–999 | date=December 2000 | doi=10.1086/317850 | bibcode=2000ApJ...545..992B | doi-access=free}}</ref>

<ref name="aj135_1_209">{{citation | display-authors=1 | last1=Massarotti | first1=Alessandro | last2=Latham | first2=David W. | last3=Stefanik | first3=Robert P. | last4=Fogel | first4=Jeffrey | title=Rotational and Radial Velocities for a Sample of 761 HIPPARCOS Giants and the Role of Binarity | journal=The Astronomical Journal | volume=135 | issue=1 | pages=209–231 |date=January 2008 | doi=10.1088/0004-6256/135/1/209 | bibcode=2008AJ....135..209M | doi-access=free}}</ref>

<ref name="mnras172_667">{{citation | last1=Jennens | first1=P. A. | last2=Helfer | first2=H. L. | title=A new photometric metal abundance and luminosity calibration for field G and K giants. | journal=[[Monthly Notices of the Royal Astronomical Society]] | volume=172 | pages=667–679 |date=September 1975 | issue=3 | bibcode=1975MNRAS.172..667J | doi=10.1093/mnras/172.3.667| doi-access=free}}</ref>

<ref name="al34_1_17">{{citation | title=Inaccuracies in the spectral classification of stars from the Tycho-2 Spectral Type Catalogue | display-authors=1 | last1=Tsvetkov | first1=A. S. | last2=Popov | first2=A. V. | last3=Smirnov | first3=A. A. | journal=Astronomy Letters | volume=34 | issue=1 | pages=17–27 | date=January 2008 | doi=10.1134/S1063773708010039 | s2cid=119468042 | bibcode=2008AstL...34...17T}}</ref>

<ref name="aj139_1105">{{citation | last=Tolbert | first=Charles Ray | title=A UBV Study of 94 Wide Visual Binaries | journal=Astrophysical Journal | volume=139 | page=1105 |date=May 1964 | doi=10.1086/147852 | bibcode=1964ApJ...139.1105T | doi-access=free}}</ref>

<ref name="kaler">{{citation | title=DELTA BOO (Delta Bootis) | first=James B. | last=Kaler | work=Stars | publisher=[[University of Illinois]] | url=http://stars.astro.illinois.edu/sow/deltaboo.html | access-date=2012-01-05}}</ref>

<ref name="robson2005">{{citation | first=Vivian E. | last=Robson | title=The Fixed Stars and Constellations in Astrology | publisher=Astrology Center of America | year=2005 | isbn=1-933303-13-1 | page=112 | url=https://books.google.com/books?id=me7_4RdVwxsC&pg=PA112}}</ref>

<ref name="brightness">The actual brightness ratio is given by 2.512Δ''m'', where Δ''m'' is the difference in magnitude. For this pair, Δ''m'' = –4.33, so the ratio is 2.512−4.33 = 0.019. Hence the secondary component is 1.9% as bright as the primary.</ref>

<ref name="csiro">{{citation |title=The Colour of Stars |date=December 21, 2004 |work=Australia Telescope, Outreach and Education |publisher=[[Commonwealth Scientific and Industrial Research Organisation]] |url=http://outreach.atnf.csiro.au/education/senior/astrophysics/photometry_colour.html |access-date=2012-01-16 |url-status=dead |archive-url=https://web.archive.org/web/20120318151427/http://outreach.atnf.csiro.au/education/senior/astrophysics/photometry_colour.html |archive-date=2012-03-18}}</ref>

<ref name="Luck2015">{{citation | title=Abundances in the Local Region. I. G and K Giants | last=Luck | first=R. Earle | journal=Astronomical Journal | volume=150 | issue=3 | at=88 | year=2015 | doi=10.1088/0004-6256/150/3/88 | arxiv=1507.01466 | bibcode=2015AJ....150...88L | s2cid=118505114 | postscript=.}}</ref>

<ref name="Soubiran_et_al_2008">{{citation | postscript=. | title=Vertical distribution of Galactic disk stars. IV. AMR and AVR from clump giants | last1=Soubiran | first1=C. | last2=Bienaymé | first2=O. | last3=Mishenina | first3=T. V. | last4=Kovtyukh | first4=V. V. | display-authors=1 | journal=Astronomy and Astrophysics | year=2008 | volume=480 | issue=1 | pages=91–101 | bibcode=2008A&A...480...91S | s2cid=16602121 | doi=10.1051/0004-6361:20078788 | arxiv=0712.1370}}</ref>

<ref name="English2014">{{citation | postscript=. | title=Grab 'n' Go Astronomy | first=Neil | last=English | date=May 14, 2014 | page=214 | isbn=9781493908264 | publisher=Springer New York | bibcode=2014gnga.book.....E | url=https://books.google.com/books?id=0mkgBAAAQBAJ&pg=PA214}}</ref>

<ref name=xhip>{{Cite XHIP | 74666 | mode=cs2 | postscript=.}}</ref>

<ref name=Princeps>{{citation | postscript=. | title=Princeps – Constellations of Words | url=https://www.constellationsofwords.com/princeps/ | access-date=2022-10-28 | language=en-US }}</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/Bootes*.html | page=103-104 }}</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=IAU-CSN>{{cite web |title=IAU Catalog of Star Names |url=https://exopla.net/star-names/modern-iau-star-names/ |access-date=20 April 2026}}</ref>

}}

==External links== * [http://webviz.u-strasbg.fr/viz-bin/VizieR-S?HR%205681 HR 5681] * [http://webviz.u-strasbg.fr/viz-bin/VizieR-S?CCDM%20J15156%2b3319A CCDM J15156+3319] * [http://aladin.u-strasbg.fr/AladinPreview?-c=15+15+30.1630%2B33+18+53.401&ident=SV*+ZI++1109&submit=Aladin+previewer Image Delta Boötis]

[[Category:G-type giants]] [[Category:G-type main-sequence stars]] [[Category:Binary stars]] [[Category:Boötes]] [[Category:Bayer objects|Bootis, Delta]] [[Category:Bright Star Catalogue objects|5681]] [[Category:Durchmusterung objects|BD+33 2561]] [[Category:Flamsteed objects|Bootis, 49]] [[Category:Henry Draper Catalogue objects|135722]] [[Category:Hipparcos objects|074666]] [[Category:Stars with proper names|Qigong]]