{{short description|Binary star system 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=υ Draconis |x=258|y=495 }} | caption = Location of υ Draconis (circled in red) }} {{Starbox observe | epoch = [[J2000.0]] | equinox = [[J2000.0]] ([[International Celestial Reference System|ICRS]]) | constell = [[Draco (constellation)|Draco]] | ra = {{RA|18|54|23.85632}}<ref name=vanLeeuwen2007/> | dec = {{DEC|+71|17|49.8906}}<ref name=vanLeeuwen2007/> | appmag_v = 4.827<ref name=Luck2007/> }} {{Starbox character | class = K0 III<ref name=Eggen1962/> | b-v = +1.15<ref name=Johnson1966/> | u-b = +1.10<ref name=Johnson1966/> | r-i = | variable = }} {{Starbox astrometry | radial_v = −11.1<ref name=Luck2007/> | prop_mo_ra = +49.53<ref name=vanLeeuwen2007/> | prop_mo_dec = +42.11<ref name=vanLeeuwen2007/> | parallax = 9.48 | p_error = 0.45 | parallax_footnote = <ref name=vanLeeuwen2007/> | absmag_v = | absmag_bol = −0.70<ref name=Luck2007/> }} {{Starbox orbit | reference = <ref name=Pourbaiz2004/> | period_unitless = 258.48 d | eccentricity = 0.21 | periastron = 2441977.5 JD | periarg = 298 | k1 = 6.0 }} {{Starbox detail | source = | mass = 2.05<ref name=Luck2015/> | radius = 19<ref name=lang2006/> | luminosity = 170<ref name=Luck2015/> | temperature = {{Val|4561|61|fmt=commas}}<ref name=Luck2015/> | gravity = 2.53<ref name=Luck2007/> | metal_fe = +0.01<ref name=Luck2007/> | rotational_velocity = | age_gyr = 1.37<ref name=Luck2015/> }} {{Starbox catalog | names = {{odlist|B=υ Dra | F=52 Dra | BD=+71°915 | FK5= | HD=176524 | HIP=92782 | HR=7180 | SAO=9283 }}<ref name=SIMBAD/> }} {{Starbox reference | Simbad = ups+Dra }} {{Starbox end}} '''Upsilon Draconis''' ('''υ Dra''') is a [[binary star]]<ref name=Pourbaiz2004/> system in the northern [[circumpolar constellation]] of [[Draco (constellation)|Draco]]. It is faintly visible to the naked eye with an [[apparent visual magnitude]] of 4.83.<ref name=Luck2007/> Based upon an annual [[stellar parallax|parallax shift]] of 9.48 [[milliarcsecond|mas]] as measured from Earth, it is located around 340 [[light year]]s (104 [[parsecs]]) from the [[Sun]]. At that distance, the visual magnitude of the star is diminished by an [[extinction (astronomy)|extinction factor]] of 0.02 due to [[interstellar dust]].<ref name=Famaey2005/>
In [[Chinese astronomy|Chinese]], {{lang|zh|紫微左垣}} ({{lang|zh-Latn|Zǐ Wēi Zuǒ Yuán}}), meaning ''[[Purple Forbidden enclosure|Left Wall of Purple Forbidden Enclosure]]'', refers to an asterism consisting of υ Draconis, [[Iota Draconis|ι Draconis]], [[Eta Draconis|η Draconis]], [[Zeta Draconis|ζ Draconis]], [[Theta Draconis|θ Draconis]], [[73 Draconis]], [[Gamma Cephei|γ Cephei]] and [[23 Cassiopeiae]].<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>
This is a single-lined [[spectroscopic binary]] star system with an [[orbital period]] of 258.48 days and an [[orbital eccentricity|eccentricity]] of 0.21.<ref name=Pourbaiz2004/> The primary, component A, is an [[stellar evolution|evolved]] [[K-type star|K-type]] [[giant star]] with a [[stellar classification]] of K0 III.<ref name=Eggen1962/> It is a suspected [[barium star]], which may indicate the orbiting companion, component B, is a [[white dwarf]] star.<ref name=Zacs1977/>
The measured [[angular diameter]] of the primary, after correction for [[limb darkening]], is {{Val|1.69|0.02|u=[[milliarcsecond|mas]]}}.<ref name=Richichi2005/> At the estimated distance of Upsilon Draconis, this yields a physical size of about 19 times the [[Sun's radius]].<ref name=lang2006/> It is about 1.37 billion years old with an estimated 2.05 times the [[mass of the Sun]].<ref name=Luck2015/> The star is radiating 170 times the [[solar luminosity]] from its [[photosphere]] at an [[effective temperature]] of 4,561 K.<ref name=Luck2015/>
==References== <references> <ref name=vanLeeuwen2007>{{citation | title=Validation of the new Hipparcos reduction | last1=van Leeuwen | first1=F. | journal=Astronomy and Astrophysics | volume=474 | issue=2 | pages=653–664 | date=2007 | arxiv=0708.1752 | bibcode=2007A&A...474..653V | doi=10.1051/0004-6361:20078357 | s2cid=18759600 | postscript=. }}</ref>
<ref name=Zacs1977>{{citation | display-authors=1 | title=An abundance analysis of the single-lined spectroscopic binaries with barium stars-like orbital elements. I. Analysis and results | last1=Zacs | first1=L. | last2=Musaev | first2=F. A. | last3=Bikmaev | first3=I. F. | last4=Alksnis | first4=O. | journal=Astronomy & Astrophysics Supplement Series | postscript=. | volume=122 | date=April 1997 | pages=31–42 | doi=10.1051/aas:1997330 | bibcode=1997A&AS..122...31Z | doi-access=free }}</ref>
<ref name=Richichi2005>{{citation | last1=Richichi | first1=A. | last2=Percheron | first2=I. | last3=Khristoforova | first3=M. | title=CHARM2: An updated Catalog of High Angular Resolution Measurements | journal=Astronomy and Astrophysics | postscript=. | volume=431 | issue=2 | pages=773–777 | date=February 2005 | doi=10.1051/0004-6361:20042039 | bibcode=2005A&A...431..773R | doi-access=free }}</ref>
<ref name=lang2006>{{citation | first1=Kenneth R. | last1=Lang | title=Astrophysical formulae | volume=1 | series=Astronomy and astrophysics library | edition=3rd | publisher=[[Birkhäuser]] | date=2006 | isbn=3-540-29692-1 | postscript=. | url=https://books.google.com/books?id=OvTjLcQ4MCQC&pg=PA41 }} The radius (R<sub>*</sub>) is given by: :<math>\begin{align} 2\cdot R_* & = \frac{(105.5\cdot 1.69\cdot 10^{-3})\ \text{AU}}{0.0046491\ \text{AU}/R_{\bigodot}} \\ & \approx 38\cdot R_{\bigodot} \end{align}</math></ref>
<ref name=Famaey2005>{{citation | display-authors=1 | last1=Famaey | first1=B. | last2=Jorissen | first2=A. | last3=Luri | first3=X. | last4=Mayor | first4=M. | last5=Udry | first5=S. | last6=Dejonghe | first6=H. | last7=Turon | first7=C. | title=Local kinematics of K and M giants from CORAVEL/Hipparcos/Tycho-2 data. Revisiting the concept of superclusters | journal=Astronomy and Astrophysics | volume=430 | pages=165–186 | date=January 2005 | doi=10.1051/0004-6361:20041272 | bibcode=2005A&A...430..165F | arxiv=astro-ph/0409579 | s2cid=17804304 | postscript=. }}</ref>
<ref name=Luck2015>{{citation | title=Abundances in the Local Region. I. G and K Giants | last1=Luck | first1=R. Earle | journal=Astronomical Journal | postscript=. | volume=150 | issue=3 | at=88 | year=2015 | bibcode=2015AJ....150...88L | doi=10.1088/0004-6256/150/3/88 |arxiv = 1507.01466 | s2cid=118505114 }}</ref>
<ref name=Pourbaiz2004>{{citation | bibcode=2004A&A...424..727P | doi=10.1051/0004-6361:20041213 | arxiv=astro-ph/0406573 | postscript=. | title=SB9: The ninth catalogue of spectroscopic binary orbits | journal=Astronomy and Astrophysics | volume=424 | issue=2 | pages=727–732 | year=2004 | last1=Pourbaix | first1=D. | last2=Tokovinin | first2=A. A. | last3=Batten | first3=A. H. | last4=Fekel | first4=F. C. | last5=Hartkopf | first5=W. I. | last6=Levato | first6=H. | last7=Morrell | first7=N. I. | last8=Torres | first8=G. | last9=Udry | first9=S. | s2cid=119387088 | display-authors=1 }}</ref>
<ref name=Luck2007>{{citation | title=Giants in the Local Region | last1=Luck | first1=R. Earle | last2=Heiter | first2=Ulrike | journal=The Astronomical Journal | postscript=. | volume=133 | issue=6 | pages=2464–2486 | date=June 2007 | doi=10.1086/513194 | bibcode=2007AJ....133.2464L | doi-access=free }}</ref>
<ref name=Eggen1962>{{citation | last1=Eggen | first1=O. J. | title=Space-velocity vectors for 3483 stars with proper motion and radial velocity | journal=Royal Observatory Bulletin | volume=51 | year=1962 | page=79 | bibcode=1962RGOB...51...79E | postscript=. }}</ref>
<ref name=Johnson1966>{{citation | display-authors=1 | last1=Johnson | first1=H. L. | last2=Iriarte | first2=B. | last3=Mitchell | first3=R. I. | last4=Wisniewskj | first4=W. Z. | title=UBVRIJKL photometry of the bright stars | journal=Communications of the Lunar and Planetary Laboratory | volume=4 | issue=99 | year=1966 | page=99 | bibcode=1966CoLPL...4...99J | postscript=. }}</ref>
<ref name=SIMBAD>{{citation | title=ups Dra -- Spectroscopic binary | work=SIMBAD Astronomical Database | publisher=Centre de Données astronomiques de Strasbourg | url=http://simbad.u-strasbg.fr/simbad/sim-id?Ident=ups+Dra | access-date=2017-05-30 | postscript=. }}</ref> </references>
{{Stars of Draco|state=collapsed}}
[[Category:K-type giants]] [[Category:Barium stars]] [[Category:Draco (constellation)]] [[Category:Bayer objects|Draconis, Upsilon]] [[Category:Durchmusterung objects|BD+71 0915]] [[Category:Flamsteed objects|Draconis, 52]] [[Category:Henry Draper Catalogue objects|176524]] [[Category:Hipparcos objects|092782]] [[Category:Bright Star Catalogue objects|7180]] [[Category:Spectroscopic binaries]]